2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Tetsuo Handa <[email protected]> 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 <[email protected]> Signed-off-by: David Howells <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Andi Kleen <[email protected]> --- kernel/cred.c | 12 ++++++++---- security/selinux/hooks.c | 6 +++++- 2 files changed, 13 insertions(+), 5 deletions(-) Index: linux-2.6.35.y/kernel/cred.c =================================================================== --- linux-2.6.35.y.orig/kernel/cred.c 2011-03-29 22:51:20.320203225 -0700 +++ linux-2.6.35.y/kernel/cred.c 2011-03-29 23:54:51.139693889 -0700 @@ -256,13 +256,13 @@ #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: @@ -754,7 +754,11 @@ 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) == Index: linux-2.6.35.y/security/selinux/hooks.c =================================================================== --- linux-2.6.35.y.orig/security/selinux/hooks.c 2011-03-29 23:02:59.725307200 -0700 +++ linux-2.6.35.y/security/selinux/hooks.c 2011-03-29 23:03:00.712281944 -0700 @@ -3234,7 +3234,11 @@ { 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); } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
