Messages in this thread | | | Date | Thu, 12 Jan 2012 10:45:30 +0800 | Subject | Re: [PATCH] proc: fix null pointer deref in proc_pid_permission() | From | Xiaotian Feng <> |
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On Thu, Jan 12, 2012 at 6:41 AM, Kees Cook <keescook@chromium.org> wrote: > On Wed, Jan 11, 2012 at 1:58 PM, Andrew Morton > <akpm@linux-foundation.org> wrote: >> On Wed, 11 Jan 2012 12:43:30 -0800 >> Kees Cook <keescook@chromium.org> wrote: >>> On Wed, Jan 11, 2012 at 01:47:05PM -0500, Xiaotian Feng wrote: >>> > get_proc_task() can fail to search the task and return NULL, put_task_struct() >>> > will then bomb the kernel with following oops: >>> > >>> > [ 1870.574045] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 >>> > [ 1870.574065] IP: [<ffffffff81217d34>] proc_pid_permission+0x64/0xe0 >>> > [ 1870.574088] PGD 112075067 PUD 112814067 PMD 0 >>> > [ 1870.574106] Oops: 0002 [#1] PREEMPT SMP >>> > >>> > This is a regression introduced by commit 0499680a, kernel should >>> > return -ESRCH if get_proc_task() failed. >>> >>> Nice catch! >>> >>> However since this error is returned to userspace, shouldn't this be >>> -ENOENT instead? >> >> Failed get_proc_task() frequently results in -ESRCH. And less >> frequently results in -ENOENT. >> >> It seems odd that inode_operations.permission() would ever return >> anything other than zero or -EPERM. > > Right, but won't this show up at ESRCH from open(2)? If this is used > as-is, we just need to have the manpages updated. >
You're right, some of get_proc_task() returns -ENOENT. Maybe we should return -ENOENT to avoid breaking userspace tools. Andrew?
> -Kees > > -- > Kees Cook > ChromeOS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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