From: Andreas Gruenbacher agruenba@redhat.com
[ Upstream commit 4e58543e7da4859c4ba61d15493e3522b6ad71fd ]
It turns out that the .freeze_super and .thaw_super operations require the filesystem to manage the superblock refcount itself. We are using the freeze_super() and thaw_super() helpers to mostly take care of that for us, but this means that the superblock may no longer be around by when thaw_super() returns, and gfs2_thaw_super() will then access freed memory. Take an extra superblock reference in gfs2_thaw_super() to fix that.
Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/gfs2/super.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 15e757f76380..e6aa7e279785 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -770,6 +770,7 @@ static int gfs2_freeze(struct super_block *sb) goto out; }
+ atomic_inc(&sb->s_active); for (;;) { error = gfs2_lock_fs_check_clean(sdp, &sdp->sd_freeze_gh); if (!error) @@ -786,6 +787,7 @@ static int gfs2_freeze(struct super_block *sb) set_bit(SDF_FS_FROZEN, &sdp->sd_flags); out: mutex_unlock(&sdp->sd_freeze_mutex); + deactivate_super(sb); return error; }