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

Greg Kroah-Hartman
2020-02-10T12:58:44Z

From: Abhi Das <adas@redhat.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@vger.kernel.org # v5.2+
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;