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Commit 6a253f38 authored by Anant Thazhemadam's avatar Anant Thazhemadam Committed by Greg Kroah-Hartman
Browse files

gfs2: add validation checks for size of superblock 



[ 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: default avatar <syzbot+af90d47a37376844e731@syzkaller.appspotmail.com>
Tested-by: default avatar <syzbot+af90d47a37376844e731@syzkaller.appspotmail.com>
Suggested-by: default avatarAndrew Price <anprice@redhat.com>
Signed-off-by: default avatarAnant Thazhemadam <anant.thazhemadam@gmail.com>
[Minor code reordering.]
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent d808c88f

fs/gfs2/ops_fstype.c

+11 −7
Original line number Diff line number Diff line
@@ -161,17 +161,21 @@ 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)

		return 0;



	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_bsize < 512 || sb->sb_bsize > PAGE_SIZE ||

	    (sb->sb_bsize & (sb->sb_bsize - 1))) {

		pr_warn("Invalid superblock size\n");

		return -EINVAL;

	}



	return 0;

}



static void end_bio_io_page(struct bio *bio)

{

	struct page *page = bio->bi_private;