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Memory for 'struct omfs_extent' and a 'e_extent_count' number of extent
entries is indirectly allocated through 'bh->b_data', which is a pointer
to data within the page. This implies that the member 'e_entry'
(which is the start of extent entries) functions more like an array than
a single object of type 'struct omfs_extent_entry'.
So we better turn this object into a proper array, in this case a
flexible-array member, and with that, fix the following
-Wstringop-overflow warning seen after building s390 architecture with
allyesconfig (GCC 13):
fs/omfs/file.c: In function 'omfs_grow_extent':
include/linux/fortify-string.h:57:33: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=]
57 | #define __underlying_memcpy __builtin_memcpy
| ^
include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy'
648 | __underlying_##op(p, q, __fortify_size); \
| ^~~~~~~~~~~~~
include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk'
693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
| ^~~~~~~~~~~~~~~~~~~~
fs/omfs/file.c:170:9: note: in expansion of macro 'memcpy'
170 | memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
| ^~~~~~
In file included from fs/omfs/omfs.h:8,
from fs/omfs/file.c:11:
fs/omfs/omfs_fs.h:80:34: note: at offset 16 into destination object 'e_entry' of size 16
80 | struct omfs_extent_entry e_entry; /* start of extent entries */
| ^~~~~~~
There are some binary differences before and after changes, but this are
expected due to the change in the size of 'struct omfs_extent' and the
necessary adjusments.
This helps with the ongoing efforts to globally enable
-Wstringop-overflow.
Link: https://github.com/KSPP/linux/issues/330
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
84 lines
2.5 KiB
C
84 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _OMFS_FS_H
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#define _OMFS_FS_H
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/* OMFS On-disk structures */
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#define OMFS_MAGIC 0xC2993D87
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#define OMFS_IMAGIC 0xD2
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#define OMFS_DIR 'D'
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#define OMFS_FILE 'F'
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#define OMFS_INODE_NORMAL 'e'
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#define OMFS_INODE_CONTINUATION 'c'
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#define OMFS_INODE_SYSTEM 's'
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#define OMFS_NAMELEN 256
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#define OMFS_DIR_START 0x1b8
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#define OMFS_EXTENT_START 0x1d0
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#define OMFS_EXTENT_CONT 0x40
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#define OMFS_XOR_COUNT 19
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#define OMFS_MAX_BLOCK_SIZE 8192
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#define OMFS_MAX_CLUSTER_SIZE 8
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#define OMFS_MAX_BLOCKS (1ul << 31)
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struct omfs_super_block {
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char s_fill1[256];
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__be64 s_root_block; /* block number of omfs_root_block */
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__be64 s_num_blocks; /* total number of FS blocks */
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__be32 s_magic; /* OMFS_MAGIC */
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__be32 s_blocksize; /* size of a block */
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__be32 s_mirrors; /* # of mirrors of system blocks */
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__be32 s_sys_blocksize; /* size of non-data blocks */
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};
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struct omfs_header {
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__be64 h_self; /* FS block where this is located */
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__be32 h_body_size; /* size of useful data after header */
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__be16 h_crc; /* crc-ccitt of body_size bytes */
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char h_fill1[2];
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u8 h_version; /* version, always 1 */
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char h_type; /* OMFS_INODE_X */
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u8 h_magic; /* OMFS_IMAGIC */
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u8 h_check_xor; /* XOR of header bytes before this */
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__be32 h_fill2;
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};
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struct omfs_root_block {
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struct omfs_header r_head; /* header */
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__be64 r_fill1;
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__be64 r_num_blocks; /* total number of FS blocks */
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__be64 r_root_dir; /* block # of root directory */
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__be64 r_bitmap; /* block # of free space bitmap */
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__be32 r_blocksize; /* size of a block */
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__be32 r_clustersize; /* size allocated for data blocks */
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__be64 r_mirrors; /* # of mirrors of system blocks */
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char r_name[OMFS_NAMELEN]; /* partition label */
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};
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struct omfs_inode {
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struct omfs_header i_head; /* header */
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__be64 i_parent; /* parent containing this inode */
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__be64 i_sibling; /* next inode in hash bucket */
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__be64 i_ctime; /* ctime, in milliseconds */
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char i_fill1[35];
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char i_type; /* OMFS_[DIR,FILE] */
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__be32 i_fill2;
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char i_fill3[64];
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char i_name[OMFS_NAMELEN]; /* filename */
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__be64 i_size; /* size of file, in bytes */
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};
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struct omfs_extent_entry {
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__be64 e_cluster; /* start location of a set of blocks */
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__be64 e_blocks; /* number of blocks after e_cluster */
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};
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struct omfs_extent {
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__be64 e_next; /* next extent table location */
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__be32 e_extent_count; /* total # extents in this table */
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__be32 e_fill;
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struct omfs_extent_entry e_entry[]; /* start of extent entries */
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};
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#endif
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