[PATCH 5.10 114/157] gfs2: bypass signal_our_withdraw if no journal

Greg Kroah-Hartman
2021-03-22T12:50:34Z

From: Bob Peterson <rpeterso@redhat.com>

[ Upstream commit d5bf630f355d8c532bef2347cf90e8ae60a5f1bd ]

Before this patch, function signal_our_withdraw referenced the journal
inode immediately. But corrupt file systems may have some invalid
journals, in which case our attempt to read it in will withdraw and the
resulting signal_our_withdraw would dereference the NULL value.

This patch adds a check to signal_our_withdraw so that if the journal
has not yet been initialized, it simply returns and does the old-style
withdraw.

Thanks, Andy Price, for his analysis.

Reported-by: syzbot+50a8a9cf8127f2c6f5df@syzkaller.appspotmail.com
Fixes: 601ef0d52e96 ("gfs2: Force withdraw to replay journals and wait for it to finish")
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/util.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/gfs2/util.c b/fs/gfs2/util.c
index a1ecb2b48250..3ece99e6490c 100644
--- a/fs/gfs2/util.c
+++ b/fs/gfs2/util.c
@@ -119,17 +119,22 @@ void gfs2_freeze_unlock(struct gfs2_holder *freeze_gh)
static void signal_our_withdraw(struct gfs2_sbd *sdp)
{
struct gfs2_glock *live_gl = sdp->sd_live_gh.gh_gl;
- struct inode *inode = sdp->sd_jdesc->jd_inode;
- struct gfs2_inode *ip = GFS2_I(inode);
- struct gfs2_glock *i_gl = ip->i_gl;
- u64 no_formal_ino = ip->i_no_formal_ino;
+ struct inode *inode;
+ struct gfs2_inode *ip;
+ struct gfs2_glock *i_gl;
+ u64 no_formal_ino;
int log_write_allowed = test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
int ret = 0;
int tries;

- if (test_bit(SDF_NORECOVERY, &sdp->sd_flags))
+ if (test_bit(SDF_NORECOVERY, &sdp->sd_flags) || !sdp->sd_jdesc)
return;

+ inode = sdp->sd_jdesc->jd_inode;
+ ip = GFS2_I(inode);
+ i_gl = ip->i_gl;
+ no_formal_ino = ip->i_no_formal_ino;
+
/* Prevent any glock dq until withdraw recovery is complete */
set_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags);
/*
--
2.30.1