linux/fs/squashfs/xattr.h
Phillip Lougher f37aa4c736 squashfs: add more sanity checks in id lookup
Sysbot has reported a number of "slab-out-of-bounds reads" and
"use-after-free read" errors which has been identified as being caused
by a corrupted index value read from the inode.  This could be because
the metadata block is uncompressed, or because the "compression" bit has
been corrupted (turning a compressed block into an uncompressed block).

This patch adds additional sanity checks to detect this, and the
following corruption.

1. It checks against corruption of the ids count.  This can either
   lead to a larger table to be read, or a smaller than expected
   table to be read.

   In the case of a too large ids count, this would often have been
   trapped by the existing sanity checks, but this patch introduces
   a more exact check, which can identify too small values.

2. It checks the contents of the index table for corruption.

Link: https://lkml.kernel.org/r/20210204130249.4495-3-phillip@squashfs.org.uk
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: syzbot+b06d57ba83f604522af2@syzkaller.appspotmail.com
Reported-by: syzbot+c021ba012da41ee9807c@syzkaller.appspotmail.com
Reported-by: syzbot+5024636e8b5fd19f0f19@syzkaller.appspotmail.com
Reported-by: syzbot+bcbc661df46657d0fa4f@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-09 17:26:44 -08:00

42 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2010
* Phillip Lougher <phillip@squashfs.org.uk>
*
* xattr.h
*/
#ifdef CONFIG_SQUASHFS_XATTR
extern __le64 *squashfs_read_xattr_id_table(struct super_block *, u64,
u64 *, int *);
extern int squashfs_xattr_lookup(struct super_block *, unsigned int, int *,
unsigned int *, unsigned long long *);
#else
static inline __le64 *squashfs_read_xattr_id_table(struct super_block *sb,
u64 start, u64 *xattr_table_start, int *xattr_ids)
{
struct squashfs_xattr_id_table *id_table;
id_table = squashfs_read_table(sb, start, sizeof(*id_table));
if (IS_ERR(id_table))
return (__le64 *) id_table;
*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
kfree(id_table);
ERROR("Xattrs in filesystem, these will be ignored\n");
return ERR_PTR(-ENOTSUPP);
}
static inline int squashfs_xattr_lookup(struct super_block *sb,
unsigned int index, int *count, unsigned int *size,
unsigned long long *xattr)
{
return 0;
}
#define squashfs_listxattr NULL
#define squashfs_xattr_handlers NULL
#endif