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gfs2: Don't leave s_fs_info pointing to freed memory in init_sbd

PATCH New Andrew Price 2 participants 2 messages Oct 8, 2018 GFS2 file system

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#0 lore raw

PATCH 1/1 gfs2: Don't leave s_fs_info pointing to freed memory in init_sbd

When alloc_percpu() fails, sdp gets freed but sb->s_fs_info still points to the same address. Move the assignment after that error check so that s_fs_info can only point to a valid sdp or NULL, which is checked for later in the error path, in gfs2_kill_super().

Reported-by syzbot+dcb8b3587445007f5808 at syzkaller.appspotmail.com
---
 fs/gfs2/ops_fstype.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
fs/gfs2/ops_fstype.c +1 -1
index c2469833b4fb..4ec69d9783a8 100644
@@ -72,13 +72,13 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
 	if (!sdp)
 		return NULL;
 
-	sb->s_fs_info = sdp;
 	sdp->sd_vfs = sb;
 	sdp->sd_lkstats = alloc_percpu(struct gfs2_pcpu_lkstats);
 	if (!sdp->sd_lkstats) {
 		kfree(sdp);
 		return NULL;
 	}
+	sb->s_fs_info = sdp;
 
 	set_bit(SDF_NOJOURNALID, &sdp->sd_flags);
 	gfs2_tune_init(&sdp->sd_tune);
Signature · 1 line
2.17.1
#1 lore raw

PATCH 1/1 gfs2: Don't leave s_fs_info pointing to freed memory in init_sbd

----- Original Message -----

Quoted 8 lines

When alloc_percpu() fails, sdp gets freed but sb->s_fs_info still points to the same address. Move the assignment after that error check so that s_fs_info can only point to a valid sdp or NULL, which is checked for later in the error path, in gfs2_kill_super().

Reported-by syzbot+dcb8b3587445007f5808 at syzkaller.appspotmail.com

---

Hi,

Thanks. This is now pushed to the for-next branch of the linux-gfs2 tree:
https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git/commit/fs/gfs2?h=for-next&id=4c62bd9cea7bcf10292f7e4c57a2bca332942697

Regards,

Bob Peterson
Red Hat File Systems