[PATCH 3.12 053/122] pstore: skip zero size persistent ram buffer in traverse

[Jiri Slaby]

From: Liu ShuoX <shuox.liu@xxxxxxxxx>

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

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

commit aa9a4a1edfbd3d223af01db833da2f07850bc655 upstream.

In ramoops_pstore_read, a valid prz pointer with zero size buffer will
break traverse of all persistent ram buffers.  The latter buffer might be
lost.

Signed-off-by: Liu ShuoX <shuox.liu@xxxxxxxxx>
Cc: "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: HuKeping <hukeping@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 fs/pstore/ram.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 36ffe55b579d..808435a9e2e1 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -126,12 +126,12 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
 
 	prz = przs[i];
 
-	if (update) {
-		/* Update old/shadowed buffer. */
+	/* Update old/shadowed buffer. */
+	if (update)
 		persistent_ram_save_old(prz);
-		if (!persistent_ram_old_size(prz))
-			return NULL;
-	}
+
+	if (!persistent_ram_old_size(prz))
+		return NULL;
 
 	*typep = type;
 	*id = i;
-- 
2.2.2

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