From: Fedor Pchelkin pchelkin@ispras.ru
[ Upstream commit 72e544b1b28325fe78a4687b980871a7e4101f76 ]
While mounting a corrupted filesystem, a signed integer '*xattr_ids' can become less than zero. This leads to the incorrect computation of 'len' and 'indexes' values which can cause null-ptr-deref in copy_bio_to_actor() or out-of-bounds accesses in the next sanity checks inside squashfs_read_xattr_id_table().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Link: https://lkml.kernel.org/r/20230117105226.329303-2-pchelkin@ispras.ru Fixes: 506220d2ba21 ("squashfs: add more sanity checks in xattr id lookup") Reported-by: syzbot+082fa4af80a5bb1a9843@syzkaller.appspotmail.com Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru Signed-off-by: Alexey Khoroshilov khoroshilov@ispras.ru Cc: Phillip Lougher phillip@squashfs.org.uk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/squashfs/xattr_id.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c index 7f718d2bf357..0c0d7882bcca 100644 --- a/fs/squashfs/xattr_id.c +++ b/fs/squashfs/xattr_id.c @@ -89,7 +89,7 @@ __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start, /* Sanity check values */
/* there is always at least one xattr id */ - if (*xattr_ids == 0) + if (*xattr_ids <= 0) return ERR_PTR(-EINVAL);
len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);