linux-kernel - [PATCH 5.5 209/367] gfs2: fix gfs2_find_jhead that returns uninitialized jhead with seq 0

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Message-Id: <20200210122443.669979204@linuxfoundation.org>
Date:   Mon, 10 Feb 2020 04:32:02 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Abhi Das <adas@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>
Subject: [PATCH 5.5 209/367] gfs2: fix gfs2_find_jhead that returns uninitialized jhead with seq 0

From: Abhi Das <adas@...hat.com>

commit 7582026f6f3588ecebd281965c8a71aff6fb6158 upstream.

When the first log header in a journal happens to have a sequence
number of 0, a bug in gfs2_find_jhead() causes it to prematurely exit,
and return an uninitialized jhead with seq 0. This can cause failures
in the caller. For instance, a mount fails in one test case.

The correct behavior is for it to continue searching through the journal
to find the correct journal head with the highest sequence number.

Fixes: f4686c26ecc3 ("gfs2: read journal in large chunks")
Cc: stable@...r.kernel.org # v5.2+
Signed-off-by: Abhi Das <adas@...hat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/gfs2/lops.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -422,7 +422,7 @@ static bool gfs2_jhead_pg_srch(struct gf
 
 	for (offset = 0; offset < PAGE_SIZE; offset += sdp->sd_sb.sb_bsize) {
 		if (!__get_log_header(sdp, kaddr + offset, 0, &lh)) {
-			if (lh.lh_sequence > head->lh_sequence)
+			if (lh.lh_sequence >= head->lh_sequence)
 				*head = lh;
 			else {
 				ret = true;