| From cf20bd60d3dc1438fb48dc4b20d01e9f8e530c00 Mon Sep 17 00:00:00 2001 |
| From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
| Date: Mon, 7 Feb 2011 13:36:10 +0000 |
| Subject: [PATCH] CRED: Fix BUG() upon security_cred_alloc_blank() failure |
| |
| commit 2edeaa34a6e3f2c43b667f6c4f7b27944b811695 upstream. |
| |
| In cred_alloc_blank() since 2.6.32, abort_creds(new) is called with |
| new->security == NULL and new->magic == 0 when security_cred_alloc_blank() |
| returns an error. As a result, BUG() will be triggered if SELinux is enabled |
| or CONFIG_DEBUG_CREDENTIALS=y. |
| |
| If CONFIG_DEBUG_CREDENTIALS=y, BUG() is called from __invalid_creds() because |
| cred->magic == 0. Failing that, BUG() is called from selinux_cred_free() |
| because selinux_cred_free() is not expecting cred->security == NULL. This does |
| not affect smack_cred_free(), tomoyo_cred_free() or apparmor_cred_free(). |
| |
| Fix these bugs by |
| |
| (1) Set new->magic before calling security_cred_alloc_blank(). |
| |
| (2) Handle null cred->security in creds_are_invalid() and selinux_cred_free(). |
| |
| Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
| Signed-off-by: David Howells <dhowells@redhat.com> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/kernel/cred.c b/kernel/cred.c |
| index 791c431..9a85aee 100644 |
| --- a/kernel/cred.c |
| +++ b/kernel/cred.c |
| @@ -256,13 +256,13 @@ struct cred *cred_alloc_blank(void) |
| #endif |
| |
| atomic_set(&new->usage, 1); |
| +#ifdef CONFIG_DEBUG_CREDENTIALS |
| + new->magic = CRED_MAGIC; |
| +#endif |
| |
| if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) |
| goto error; |
| |
| -#ifdef CONFIG_DEBUG_CREDENTIALS |
| - new->magic = CRED_MAGIC; |
| -#endif |
| return new; |
| |
| error: |
| @@ -816,7 +816,11 @@ bool creds_are_invalid(const struct cred *cred) |
| if (cred->magic != CRED_MAGIC) |
| return true; |
| #ifdef CONFIG_SECURITY_SELINUX |
| - if (selinux_is_enabled()) { |
| + /* |
| + * cred->security == NULL if security_cred_alloc_blank() or |
| + * security_prepare_creds() returned an error. |
| + */ |
| + if (selinux_is_enabled() && cred->security) { |
| if ((unsigned long) cred->security < PAGE_SIZE) |
| return true; |
| if ((*(u32 *)cred->security & 0xffffff00) == |
| diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c |
| index 0b459c8..c59c83f 100644 |
| --- a/security/selinux/hooks.c |
| +++ b/security/selinux/hooks.c |
| @@ -3256,7 +3256,11 @@ static void selinux_cred_free(struct cred *cred) |
| { |
| struct task_security_struct *tsec = cred->security; |
| |
| - BUG_ON((unsigned long) cred->security < PAGE_SIZE); |
| + /* |
| + * 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); |
| cred->security = (void *) 0x7UL; |
| kfree(tsec); |
| } |
| -- |
| 1.7.4.4 |
| |