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gfs2: add validation checks for size of superblock

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[ Upstream commit 0ddc5154b24c96f20e94d653b0a814438de6032b ]

In gfs2_check_sb(), no validation checks are performed with regards to
the size of the superblock.
syzkaller detected a slab-out-of-bounds bug that was primarily caused
because the block size for a superblock was set to zero.
A valid size for a superblock is a power of 2 between 512 and PAGE_SIZE.
Performing validation checks and ensuring that the size of the superblock
is valid fixes this bug.

Reported-by: syzbot+af90d47a37376844e731@syzkaller.appspotmail.com
Tested-by: syzbot+af90d47a37376844e731@syzkaller.appspotmail.com
Suggested-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
[Minor code reordering.]
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Anant Thazhemadam 2020-10-14 22:01:09 +05:30 committed by Greg Kroah-Hartman
parent d808c88f0b
commit 6a253f385a
1 changed files with 11 additions and 7 deletions
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18
fs/gfs2/ops_fstype.c
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@ -161,15 +161,19 @@ static int gfs2_check_sb(struct gfs2_sbd *sdp, int silent)
return -EINVAL;
}
/* If format numbers match exactly, we're done. */
if (sb->sb_fs_format != GFS2_FORMAT_FS ||
sb->sb_multihost_format != GFS2_FORMAT_MULTI) {
fs_warn(sdp, "Unknown on-disk format, unable to mount\n");
return -EINVAL;
}
if (sb->sb_fs_format == GFS2_FORMAT_FS &&
sb->sb_multihost_format == GFS2_FORMAT_MULTI)
return 0;
if (sb->sb_bsize < 512 || sb->sb_bsize > PAGE_SIZE ||
(sb->sb_bsize & (sb->sb_bsize - 1))) {
pr_warn("Invalid superblock size\n");
return -EINVAL;
}
fs_warn(sdp, "Unknown on-disk format, unable to mount\n");
return -EINVAL;
return 0;
}
static void end_bio_io_page(struct bio *bio)