[PATCH 3.12 041/181] xfs: fix possible NULL dereference in xlog_verify_iclog

[Jiri Slaby]

From: "Geyslan G. Bem" <geyslan@xxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 643f7c4e5656bd18c769211f933190f7bb738245 upstream.

In xlog_verify_iclog a debug check of the incore log buffers prints an
error if icptr is null and then goes on to dereference the pointer
regardless.  Convert this to an assert so that the intention is clear.
This was reported by Coverty.

Signed-off-by: Ben Myers <bpm@xxxxxxx>
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 fs/xfs/xfs_log.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 613ed9414e70..3c4ddc1c79a4 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3712,11 +3712,9 @@ xlog_verify_iclog(
 	/* check validity of iclog pointers */
 	spin_lock(&log->l_icloglock);
 	icptr = log->l_iclog;
-	for (i=0; i < log->l_iclog_bufs; i++) {
-		if (icptr == NULL)
-			xfs_emerg(log->l_mp, "%s: invalid ptr", __func__);
-		icptr = icptr->ic_next;
-	}
+	for (i = 0; i < log->l_iclog_bufs; i++, icptr = icptr->ic_next)
+		ASSERT(icptr);
+
 	if (icptr != log->l_iclog)
 		xfs_emerg(log->l_mp, "%s: corrupt iclog ring", __func__);
 	spin_unlock(&log->l_icloglock);
-- 
2.0.0

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