pstore/ram: Add check for kstrdup

Add check for the return value of kstrdup() and return the error
if it fails in order to avoid NULL pointer dereference.

Fixes: e163fdb ("pstore/ram: Regularize prz label allocation lifetime")
Signed-off-by: Jiasheng Jiang <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: JiangJias

fs/pstore/ram_core.c

@@ -599,6 +599,8 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 	raw_spin_lock_init(&prz->buffer_lock);
 	prz->flags = flags;
 	prz->label = kstrdup(label, GFP_KERNEL);
+	if (!prz->label)
+		goto err;
 
 	ret = persistent_ram_buffer_map(start, size, prz, memtype);
 	if (ret)