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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2011-02-07 13:36:10 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-02-07 14:04:00 -0800
commit2edeaa34a6e3f2c43b667f6c4f7b27944b811695 (patch)
tree37dd9156645491a86844ba9198fe05e4e6fe44c5 /kernel/cred.c
parent257a65d79581880032e0bf0c452f4041b693664c (diff)
downloadlinux-2edeaa34a6e3f2c43b667f6c4f7b27944b811695.tar.gz
CRED: Fix BUG() upon security_cred_alloc_blank() failure
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>
Diffstat (limited to 'kernel/cred.c')
-rw-r--r--kernel/cred.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/cred.c b/kernel/cred.c
index 6a1aa004e37..fcf104bb5aa 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -252,13 +252,13 @@ 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:
@@ -748,7 +748,11 @@ 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) ==