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: Jiri Slaby <jslaby@suse.cz>

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 36ffe55b579dc96489ce5daea8544281c47c8a0a..808435a9e2e1393cc2b6ed376c89738af1652ab0 100644 (file)
--- 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;