pstore: skip zero size persistent ram buffer in traverse

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>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 9fe5b13295e0..1daed280f1b6 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -120,12 +120,12 @@ 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;