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Subject[PATCH] CRED: Fix double free in prepare_usermodehelper_creds() error handling
Date
Patch 570b8fb505896e007fd3bb07573ba6640e51851d:

Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue Mar 30 00:04:00 2010 +0100
Subject: CRED: Fix memory leak in error handling

attempts to fix a memory leak in the error handling by making the offending
return statement into a jump down to the bottom of the function where a
kfree(tgcred) is inserted.

This is, however, incorrect, as it does a kfree() after doing put_cred() if
security_prepare_creds() fails. That will result in a double free if 'error'
is jumped to as put_cred() will also attempt to free the new tgcred record by
virtue of it being pointed to by the new cred record.

Signed-off-by: David Howells <dhowells@redhat.com>
---

kernel/cred.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/cred.c b/kernel/cred.c
index e1dbe9e..ce1a52b 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -398,6 +398,8 @@ struct cred *prepare_usermodehelper_creds(void)

error:
put_cred(new);
+ return NULL;
+
free_tgcred:
#ifdef CONFIG_KEYS
kfree(tgcred);


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