[PATCH 1/1] seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO
Brad Figg
brad.figg at canonical.com
Tue Mar 1 17:47:05 UTC 2016
From: Kees Cook <keescook at chromium.org>
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.
Signed-off-by: Kees Cook <keescook at chromium.org>
Reported-by: Dmitry V. Levin <ldv at altlinux.org>
Cc: Andy Lutomirski <luto at amacapital.net>
Cc: Will Drewry <wad at chromium.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Brad Figg <brad.figg at canonical.com>
---
kernel/seccomp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index bdaa55d..05e5c05 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -595,7 +595,9 @@ int __secure_computing(int this_syscall)
ret &= SECCOMP_RET_ACTION;
switch (ret) {
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, regs,
-data, 0);
goto skip;
--
2.7.0
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