* [PATCH] seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO
@ 2015-02-06 21:03 Kees Cook
2015-02-06 22:32 ` Dmitry V. Levin
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2015-02-06 21:03 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, Andy Lutomirski, Will Drewry, Dmitry V. Levin
The value resulting from the SECCOMP_RET_DATA mask could exceed MAX_ERRNO
when setting errno during a SECCOMP_RET_ERRNO filter action. This makes sure
we have a reliable value being set, so that an invalid errno will not be
ignored by userspace.
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
kernel/seccomp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4ef9687ac115..4f44028943e6 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -629,7 +629,9 @@ static u32 __seccomp_phase1_filter(int this_syscall, struct seccomp_data *sd)
switch (action) {
case SECCOMP_RET_ERRNO:
- /* Set the low-order 16-bits as a errno. */
+ /* Set low-order bits as an errno, capped at MAX_ERRNO. */
+ if (data > MAX_ERRNO)
+ data = MAX_ERRNO;
syscall_set_return_value(current, task_pt_regs(current),
-data, 0);
goto skip;
--
1.9.1
--
Kees Cook
Chrome OS Security
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO
2015-02-06 21:03 [PATCH] seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO Kees Cook
@ 2015-02-06 22:32 ` Dmitry V. Levin
0 siblings, 0 replies; 2+ messages in thread
From: Dmitry V. Levin @ 2015-02-06 22:32 UTC (permalink / raw)
To: Kees Cook; +Cc: akpm, linux-kernel, Andy Lutomirski, Will Drewry
On Fri, Feb 06, 2015 at 01:03:09PM -0800, Kees Cook wrote:
> The value resulting from the SECCOMP_RET_DATA mask could exceed MAX_ERRNO
> when setting errno during a SECCOMP_RET_ERRNO filter action. This makes sure
> we have a reliable value being set, so that an invalid errno will not be
> ignored by userspace.
Acked-by: Dmitry V. Levin <ldv@altlinux.org>
--
ldv
^ permalink raw reply [flat|nested] 2+ messages in thread
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