[PATCH 1/1] pstore/ram: Check member of buffers during the initialization phase of the pstore

[Yunlong Xing]

From: Enlin Mu <enlin.mu@xxxxxxxxxx>

The commit 30696378f68a("pstore/ram: Do not treat empty buffers as valid")
would introduce the following issue:

When finding the buffer_size is zero, it would return directly.However, at
the same time, if the buffer's start is a illegal value, the others would
panic if access the buffer.

To avoid these happenning, check if the members are legal during the
initialization phase of the pstore.

Fixes: 30696378f68a ("pstore/ram: Do not treat empty buffers as valid")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Enlin Mu <enlin.mu@xxxxxxxxxx>
---
 fs/pstore/ram_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 85aaf0fc6d7d..eb6df190d752 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -519,7 +519,7 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 	sig ^= PERSISTENT_RAM_SIG;
 
 	if (prz->buffer->sig == sig) {
-		if (buffer_size(prz) == 0) {
+		if (buffer_size(prz) == 0 && buffer_start(prz) == 0) {
 			pr_debug("found existing empty buffer\n");
 			return 0;
 		}
-- 
2.25.1