* [PATCH][RFC] Null short-circuit for selinux_cred_free()
@ 2011-03-21 21:23 Jesper Juhl
2011-03-23 3:51 ` Tetsuo Handa
0 siblings, 1 reply; 3+ messages in thread
From: Jesper Juhl @ 2011-03-21 21:23 UTC (permalink / raw)
To: Linux Kernel Mailing List
Cc: Justin Mattock, Stephen Smalley, James Morris, Eric Paris,
linux-security-module
Let selinux_cred_free accept NULL pointers.
If we don't do this, then we can crash if someone manages to pass NULL to
cred_free. Seems to me it's better to just do nothing in that case rather
than crash.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
---
hooks.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6475e1f..d2216cf 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3232,13 +3232,16 @@ static int selinux_cred_alloc_blank(struct cred *cred, gfp_t gfp)
*/
static void selinux_cred_free(struct cred *cred)
{
- struct task_security_struct *tsec = cred->security;
+ struct task_security_struct *tsec;
+ if (!cred)
+ return;
/*
* cred->security == NULL if security_cred_alloc_blank() or
* security_prepare_creds() returned an error.
*/
- BUG_ON(cred->security && (unsigned long) cred->security < PAGE_SIZE);
+ BUG_ON(cred->security && (unsigned long)cred->security < PAGE_SIZE);
+ tsec = cred->security;
cred->security = (void *) 0x7UL;
kfree(tsec);
}
--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH][RFC] Null short-circuit for selinux_cred_free()
2011-03-21 21:23 [PATCH][RFC] Null short-circuit for selinux_cred_free() Jesper Juhl
@ 2011-03-23 3:51 ` Tetsuo Handa
2011-03-23 21:07 ` Jesper Juhl
0 siblings, 1 reply; 3+ messages in thread
From: Tetsuo Handa @ 2011-03-23 3:51 UTC (permalink / raw)
To: jj; +Cc: linux-security-module, linux-kernel
Jesper Juhl wrote:
> Let selinux_cred_free accept NULL pointers.
No need to do so.
> If we don't do this, then we can crash if someone manages to pass NULL to
> cred_free. Seems to me it's better to just do nothing in that case rather
> than crash.
If cred == NULL, put_cred_rcu(NULL) causes the kernel to panic before calling
LSM hooks.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH][RFC] Null short-circuit for selinux_cred_free()
2011-03-23 3:51 ` Tetsuo Handa
@ 2011-03-23 21:07 ` Jesper Juhl
0 siblings, 0 replies; 3+ messages in thread
From: Jesper Juhl @ 2011-03-23 21:07 UTC (permalink / raw)
To: Tetsuo Handa; +Cc: linux-security-module, linux-kernel
On Wed, 23 Mar 2011, Tetsuo Handa wrote:
> Jesper Juhl wrote:
> > Let selinux_cred_free accept NULL pointers.
> No need to do so.
>
> > If we don't do this, then we can crash if someone manages to pass NULL to
> > cred_free. Seems to me it's better to just do nothing in that case rather
> > than crash.
> If cred == NULL, put_cred_rcu(NULL) causes the kernel to panic before calling
> LSM hooks.
Good point. Thanks.
--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-03-23 3:51 ` Tetsuo Handa
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