From: tip-bot for Kees Cook <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hpa@zytor.com, peterz@infradead.org, keescook@chromium.org,
jpoimboe@redhat.com, tglx@linutronix.de, luto@kernel.org,
mingo@kernel.org, bp@alien8.de, torvalds@linux-foundation.org,
dvlasenk@redhat.com, linux-kernel@vger.kernel.org,
brgerst@gmail.com, robert@swiecki.net
Subject: [tip:core/urgent] lib/syscall: Clear return values when no stack
Date: Thu, 23 Mar 2017 23:45:56 -0700 [thread overview]
Message-ID: <tip-854fbd6e5f60fe99e8e3a569865409fca378f143@git.kernel.org> (raw)
In-Reply-To: <20170323224616.GA92694@beast>
Commit-ID: 854fbd6e5f60fe99e8e3a569865409fca378f143
Gitweb: http://git.kernel.org/tip/854fbd6e5f60fe99e8e3a569865409fca378f143
Author: Kees Cook <keescook@chromium.org>
AuthorDate: Thu, 23 Mar 2017 15:46:16 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 24 Mar 2017 07:43:35 +0100
lib/syscall: Clear return values when no stack
Commit:
aa1f1a639621 ("lib/syscall: Pin the task stack in collect_syscall()")
... added logic to handle a process stack not existing, but left sp and pc
uninitialized, which can be later reported via /proc/$pid/syscall for zombie
processes, potentially exposing kernel memory to userspace.
Zombie /proc/$pid/syscall before:
-1 0xffffffff9a060100 0xffff92f42d6ad900
Zombie /proc/$pid/syscall after:
-1 0x0 0x0
Reported-by: Robert Święcki <robert@swiecki.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # v4.9+
Fixes: aa1f1a639621 ("lib/syscall: Pin the task stack in collect_syscall()")
Link: http://lkml.kernel.org/r/20170323224616.GA92694@beast
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
lib/syscall.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/syscall.c b/lib/syscall.c
index 17d5ff5..2c6cd1b 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -12,6 +12,7 @@ static int collect_syscall(struct task_struct *target, long *callno,
if (!try_get_task_stack(target)) {
/* Task has no stack, so the task isn't in a syscall. */
+ *sp = *pc = 0;
*callno = -1;
return 0;
}
prev parent reply other threads:[~2017-03-24 6:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 22:46 [PATCH] lib/syscall: Clear return values when no stack Kees Cook
2017-03-23 23:03 ` Andy Lutomirski
2017-03-24 6:45 ` tip-bot for Kees Cook [this message]
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