linux-kernel - [PATCH] audit: fix potential null dereference 'context->module.name'

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Message-Id: <1532411834-33775-1-git-send-email-wang.yi59@zte.com.cn>
Date:   Tue, 24 Jul 2018 13:57:14 +0800
From:   Yi Wang <wang.yi59@....com.cn>
To:     paul@...l-moore.com
Cc:     eparis@...hat.com, linux-audit@...hat.com,
        linux-kernel@...r.kernel.org, jiang.biao2@....com.cn,
        wang.yi59@....com.cn, zhong.weidong@....com.cn
Subject: [PATCH] audit: fix potential null dereference 'context->module.name'

The variable 'context->module.name' may be null pointer when
kmalloc return null, so it's better to check it before using
to avoid null dereference.

Signed-off-by: Yi Wang <wang.yi59@....com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@....com.cn>
---
 kernel/auditsc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index e80459f..4830b83 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1272,8 +1272,12 @@ static void show_special(struct audit_context *context, int *call_panic)
 		break;
 	case AUDIT_KERN_MODULE:
 		audit_log_format(ab, "name=");
-		audit_log_untrustedstring(ab, context->module.name);
-		kfree(context->module.name);
+		if (context->module.name) {
+			audit_log_untrustedstring(ab, context->module.name);
+			kfree(context->module.name);
+		} else
+			audit_log_format(ab, "(null)");
+
 		break;
 	}
 	audit_log_end(ab);
@@ -2409,7 +2413,8 @@ void __audit_log_kern_module(char *name)
 	struct audit_context *context = current->audit_context;
 
 	context->module.name = kmalloc(strlen(name) + 1, GFP_KERNEL);
-	strcpy(context->module.name, name);
+	if (context->module.name)
+		strcpy(context->module.name, name);
 	context->type = AUDIT_KERN_MODULE;
 }
 
-- 
1.8.3.1