Hi hackers,
I found that there's a nullable pointer being passed to strcmp() and
can make the server crash. It can be reproduced on the latest master
branch by crafting an extension[1]. Patch for fixing it is attatched.
[1] https://github.com/higuoxing/guc_crash/tree/pg
--
Best Regards,
Xing
From dcd7a49190f0e19ba0a1e697cac45724450f6365 Mon Sep 17 00:00:00 2001
From: Xing Guo <higuox...@gmail.com>
Date: Wed, 1 Nov 2023 16:41:49 +0800
Subject: [PATCH] Don't use strcmp() with nullable pointers.
Passing a NULL pointer to strcmp() is an undefined behavior. It can make
the PostgreSQL server crash. This patch helps fix it.
---
src/backend/utils/misc/guc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 39d3775e80..b277c48925 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -5255,7 +5255,9 @@ get_explain_guc_options(int *num)
{
struct config_string *lconf = (struct config_string *) conf;
- modified = (strcmp(lconf->boot_val, *(lconf->variable)) != 0);
+ modified = (lconf->boot_val == NULL ||
+ *lconf->variable == NULL ||
+ strcmp(lconf->boot_val, *(lconf->variable)) != 0);
}
break;
--
2.42.0
