[Precise] arm: oabi compat: add missing access checks
Luis Henriques
luis.henriques at canonical.com
Fri Aug 26 09:22:56 UTC 2016
From: Dave Weinstein <olorin at google.com>
Add access checks to sys_oabi_epoll_wait() and sys_oabi_semtimedop().
This fixes CVE-2016-3857, a local privilege escalation under
CONFIG_OABI_COMPAT.
Cc: stable at vger.kernel.org
Reported-by: Chiachih Wu <wuchiachih at gmail.com>
Reviewed-by: Kees Cook <keescook at chromium.org>
Reviewed-by: Nicolas Pitre <nico at linaro.org>
Signed-off-by: Dave Weinstein <olorin at google.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
CVE-2016-3857
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
arch/arm/kernel/sys_oabi-compat.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
index af0aaebf4de6..32884a6006cf 100644
--- a/arch/arm/kernel/sys_oabi-compat.c
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -275,8 +275,12 @@ asmlinkage long sys_oabi_epoll_wait(int epfd,
mm_segment_t fs;
long ret, err, i;
- if (maxevents <= 0 || maxevents > (INT_MAX/sizeof(struct epoll_event)))
+ if (maxevents <= 0 ||
+ maxevents > (INT_MAX/sizeof(*kbuf)) ||
+ maxevents > (INT_MAX/sizeof(*events)))
return -EINVAL;
+ if (!access_ok(VERIFY_WRITE, events, sizeof(*events) * maxevents))
+ return -EFAULT;
kbuf = kmalloc(sizeof(*kbuf) * maxevents, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
@@ -313,6 +317,8 @@ asmlinkage long sys_oabi_semtimedop(int semid,
if (nsops < 1 || nsops > SEMOPM)
return -EINVAL;
+ if (!access_ok(VERIFY_READ, tsops, sizeof(*tsops) * nsops))
+ return -EFAULT;
sops = kmalloc(sizeof(*sops) * nsops, GFP_KERNEL);
if (!sops)
return -ENOMEM;
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