linux-kernel - [PATCH next] audit: fix potential double free on error path from fsnotify_add_inode

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Date:   Mon, 22 Aug 2022 10:29:05 +0800
From:   Gaosheng Cui <cuigaosheng1@...wei.com>
To:     <paul@...l-moore.com>, <eparis@...hat.com>, <mszeredi@...hat.com>,
        <jack@...e.cz>, <amir73il@...il.com>, <cuigaosheng1@...wei.com>
CC:     <linux-audit@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH next] audit: fix potential double free on error path from fsnotify_add_inode_mark

Audit_alloc_mark() assign pathname to audit_mark->path, on error path
from fsnotify_add_inode_mark(), fsnotify_put_mark will free memory
of audit_mark->path, but the caller of audit_alloc_mark will free
the pathname again, so there will be double free problem.

Fix this by resetting audit_mark->path to NULL pointer on error path
from fsnotify_add_inode_mark().

Fixes: 7b1293234084d ("fsnotify: Add group pointer in fsnotify_init_mark()")
Signed-off-by: Gaosheng Cui <cuigaosheng1@...wei.com>
---
 kernel/audit_fsnotify.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/audit_fsnotify.c b/kernel/audit_fsnotify.c
index 6432a37ac1c9..c565fbf66ac8 100644
--- a/kernel/audit_fsnotify.c
+++ b/kernel/audit_fsnotify.c
@@ -102,6 +102,7 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pa
 
 	ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, 0);
 	if (ret < 0) {
+		audit_mark->path = NULL;
 		fsnotify_put_mark(&audit_mark->mark);
 		audit_mark = ERR_PTR(ret);
 	}
-- 
2.25.1