From: Liu ShuoX <shuox.liu@intel.com>
Date: Mon, 17 Mar 2014 00:24:49 +0000 (+1100)
Subject: pstore: skip zero size persistent ram buffer in traverse
X-Git-Tag: firefly_0821_release~3679^2~861
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=ca889efda7bb061eb29716ba34a3271c298eb948;p=firefly-linux-kernel-4.4.55.git

pstore: skip zero size persistent ram buffer in traverse

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@intel.com>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Cc: Colin Cross <ccross@android.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: HuKeping <hukeping@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 546fdc7d3399..e0e42b5a691c 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;