linux/fs/qnx4/dir.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
/*
* QNX4 file system, Linux implementation.
*
* Version : 0.2.1
*
* Using parts of the xiafs filesystem.
*
* History :
*
* 28-05-1998 by Richard Frowijn : first release.
* 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
*/
#include <linux/buffer_head.h>
#include "qnx4.h"
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
/*
* A qnx4 directory entry is an inode entry or link info
* depending on the status field in the last byte. The
* first byte is where the name start either way, and a
* zero means it's empty.
qnx4: work around gcc false positive warning bug In commit b7213ffa0e58 ("qnx4: avoid stringop-overread errors") I tried to teach gcc about how the directory entry structure can be two different things depending on a status flag. It made the code clearer, and it seemed to make gcc happy. However, Arnd points to a gcc bug, where despite using two different members of a union, gcc then gets confused, and uses the size of one of the members to decide if a string overrun happens. And not necessarily the rigth one. End result: with some configurations, gcc-11 will still complain about the source buffer size being overread: fs/qnx4/dir.c: In function 'qnx4_readdir': fs/qnx4/dir.c:76:32: error: 'strnlen' specified bound [16, 48] exceeds source size 1 [-Werror=stringop-overread] 76 | size = strnlen(name, size); | ^~~~~~~~~~~~~~~~~~~ fs/qnx4/dir.c:26:22: note: source object declared here 26 | char de_name; | ^~~~~~~ because gcc will get confused about which union member entry is actually getting accessed, even when the source code is very clear about it. Gcc internally will have combined two "redundant" pointers (pointing to different union elements that are at the same offset), and takes the size checking from one or the other - not necessarily the right one. This is clearly a gcc bug, but we can work around it fairly easily. The biggest thing here is the big honking comment about why we do what we do. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6 Reported-and-tested-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-20 17:26:21 +00:00
*
* Also, due to a bug in gcc, we don't want to use the
* real (differently sized) name arrays in the inode and
* link entries, but always the 'de_name[]' one in the
* fake struct entry.
*
* See
*
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
*
* for details, but basically gcc will take the size of the
* 'name' array from one of the used union entries randomly.
*
* This use of 'de_name[]' (48 bytes) avoids the false positive
* warnings that would happen if gcc decides to use 'inode.di_name'
* (16 bytes) even when the pointer and size were to come from
* 'link.dl_name' (48 bytes).
*
* In all cases the actual name pointer itself is the same, it's
* only the gcc internal 'what is the size of this field' logic
* that can get confused.
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
*/
union qnx4_directory_entry {
struct {
qnx4: work around gcc false positive warning bug In commit b7213ffa0e58 ("qnx4: avoid stringop-overread errors") I tried to teach gcc about how the directory entry structure can be two different things depending on a status flag. It made the code clearer, and it seemed to make gcc happy. However, Arnd points to a gcc bug, where despite using two different members of a union, gcc then gets confused, and uses the size of one of the members to decide if a string overrun happens. And not necessarily the rigth one. End result: with some configurations, gcc-11 will still complain about the source buffer size being overread: fs/qnx4/dir.c: In function 'qnx4_readdir': fs/qnx4/dir.c:76:32: error: 'strnlen' specified bound [16, 48] exceeds source size 1 [-Werror=stringop-overread] 76 | size = strnlen(name, size); | ^~~~~~~~~~~~~~~~~~~ fs/qnx4/dir.c:26:22: note: source object declared here 26 | char de_name; | ^~~~~~~ because gcc will get confused about which union member entry is actually getting accessed, even when the source code is very clear about it. Gcc internally will have combined two "redundant" pointers (pointing to different union elements that are at the same offset), and takes the size checking from one or the other - not necessarily the right one. This is clearly a gcc bug, but we can work around it fairly easily. The biggest thing here is the big honking comment about why we do what we do. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6 Reported-and-tested-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-20 17:26:21 +00:00
const char de_name[48];
u8 de_pad[15];
u8 de_status;
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
};
struct qnx4_inode_entry inode;
struct qnx4_link_info link;
};
static int qnx4_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
unsigned int offset;
struct buffer_head *bh;
unsigned long blknum;
int ix, ino;
int size;
QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
QNX4DEBUG((KERN_INFO "pos = %ld\n", (long) ctx->pos));
while (ctx->pos < inode->i_size) {
blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
bh = sb_bread(inode->i_sb, blknum);
if (bh == NULL) {
printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
return 0;
}
ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
union qnx4_directory_entry *de;
offset = ix * QNX4_DIR_ENTRY_SIZE;
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
de = (union qnx4_directory_entry *) (bh->b_data + offset);
qnx4: work around gcc false positive warning bug In commit b7213ffa0e58 ("qnx4: avoid stringop-overread errors") I tried to teach gcc about how the directory entry structure can be two different things depending on a status flag. It made the code clearer, and it seemed to make gcc happy. However, Arnd points to a gcc bug, where despite using two different members of a union, gcc then gets confused, and uses the size of one of the members to decide if a string overrun happens. And not necessarily the rigth one. End result: with some configurations, gcc-11 will still complain about the source buffer size being overread: fs/qnx4/dir.c: In function 'qnx4_readdir': fs/qnx4/dir.c:76:32: error: 'strnlen' specified bound [16, 48] exceeds source size 1 [-Werror=stringop-overread] 76 | size = strnlen(name, size); | ^~~~~~~~~~~~~~~~~~~ fs/qnx4/dir.c:26:22: note: source object declared here 26 | char de_name; | ^~~~~~~ because gcc will get confused about which union member entry is actually getting accessed, even when the source code is very clear about it. Gcc internally will have combined two "redundant" pointers (pointing to different union elements that are at the same offset), and takes the size checking from one or the other - not necessarily the right one. This is clearly a gcc bug, but we can work around it fairly easily. The biggest thing here is the big honking comment about why we do what we do. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6 Reported-and-tested-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-20 17:26:21 +00:00
if (!de->de_name[0])
continue;
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
continue;
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
if (!(de->de_status & QNX4_FILE_LINK)) {
size = sizeof(de->inode.di_fname);
ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
} else {
size = sizeof(de->link.dl_fname);
ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
QNX4_INODES_PER_BLOCK +
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
de->link.dl_inode_ndx;
}
qnx4: work around gcc false positive warning bug In commit b7213ffa0e58 ("qnx4: avoid stringop-overread errors") I tried to teach gcc about how the directory entry structure can be two different things depending on a status flag. It made the code clearer, and it seemed to make gcc happy. However, Arnd points to a gcc bug, where despite using two different members of a union, gcc then gets confused, and uses the size of one of the members to decide if a string overrun happens. And not necessarily the rigth one. End result: with some configurations, gcc-11 will still complain about the source buffer size being overread: fs/qnx4/dir.c: In function 'qnx4_readdir': fs/qnx4/dir.c:76:32: error: 'strnlen' specified bound [16, 48] exceeds source size 1 [-Werror=stringop-overread] 76 | size = strnlen(name, size); | ^~~~~~~~~~~~~~~~~~~ fs/qnx4/dir.c:26:22: note: source object declared here 26 | char de_name; | ^~~~~~~ because gcc will get confused about which union member entry is actually getting accessed, even when the source code is very clear about it. Gcc internally will have combined two "redundant" pointers (pointing to different union elements that are at the same offset), and takes the size checking from one or the other - not necessarily the right one. This is clearly a gcc bug, but we can work around it fairly easily. The biggest thing here is the big honking comment about why we do what we do. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6 Reported-and-tested-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-20 17:26:21 +00:00
size = strnlen(de->de_name, size);
qnx4: avoid stringop-overread errors The qnx4 directory entries are 64-byte blocks that have different contents depending on the a status byte that is in the last byte of the block. In particular, a directory entry can be either a "link info" entry with a 48-byte name and pointers to the real inode information, or an "inode entry" with a smaller 16-byte name and the full inode information. But the code was written to always just treat the directory name as if it was part of that "inode entry", and just extend the name to the longer case if the status byte said it was a link entry. That work just fine and gives the right results, but now that gcc is tracking data structure accesses much more, the code can trigger a compiler error about using up to 48 bytes (the long name) in a structure that only has that shorter name in it: fs/qnx4/dir.c: In function ‘qnx4_readdir’: fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread] 51 | size = strnlen(de->di_fname, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from fs/qnx4/qnx4.h:3, from fs/qnx4/dir.c:16: include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here 45 | char di_fname[QNX4_SHORT_NAME_MAX]; | ^~~~~~~~ which is because the source code doesn't really make this whole "one of two different types" explicit. Fix this by introducing a very explicit union of the two types, and basically explaining to the compiler what is really going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-15 20:56:37 +00:00
QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
qnx4: work around gcc false positive warning bug In commit b7213ffa0e58 ("qnx4: avoid stringop-overread errors") I tried to teach gcc about how the directory entry structure can be two different things depending on a status flag. It made the code clearer, and it seemed to make gcc happy. However, Arnd points to a gcc bug, where despite using two different members of a union, gcc then gets confused, and uses the size of one of the members to decide if a string overrun happens. And not necessarily the rigth one. End result: with some configurations, gcc-11 will still complain about the source buffer size being overread: fs/qnx4/dir.c: In function 'qnx4_readdir': fs/qnx4/dir.c:76:32: error: 'strnlen' specified bound [16, 48] exceeds source size 1 [-Werror=stringop-overread] 76 | size = strnlen(name, size); | ^~~~~~~~~~~~~~~~~~~ fs/qnx4/dir.c:26:22: note: source object declared here 26 | char de_name; | ^~~~~~~ because gcc will get confused about which union member entry is actually getting accessed, even when the source code is very clear about it. Gcc internally will have combined two "redundant" pointers (pointing to different union elements that are at the same offset), and takes the size checking from one or the other - not necessarily the right one. This is clearly a gcc bug, but we can work around it fairly easily. The biggest thing here is the big honking comment about why we do what we do. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6 Reported-and-tested-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-20 17:26:21 +00:00
if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) {
brelse(bh);
return 0;
}
}
brelse(bh);
}
return 0;
}
const struct file_operations qnx4_dir_operations =
{
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = qnx4_readdir,
.fsync = generic_file_fsync,
};
const struct inode_operations qnx4_dir_inode_operations =
{
.lookup = qnx4_lookup,
};