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From 2def2ef2ae5f3990aabdbe8a755911902707d268 Mon Sep 17 00:00:00 2001
From: PaX Team <pageexec@freemail.hu>
Date: Thu, 30 Jan 2014 16:59:25 -0800
Subject: [PATCH] x86, x32: Correct invalid use of user timespec in the kernel
The x32 case for the recvmsg() timout handling is broken:
asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
unsigned int vlen, unsigned int flags,
struct compat_timespec __user *timeout)
{
int datagrams;
struct timespec ktspec;
if (flags & MSG_CMSG_COMPAT)
return -EINVAL;
if (COMPAT_USE_64BIT_TIME)
return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
flags | MSG_CMSG_COMPAT,
(struct timespec *) timeout);
...
The timeout pointer parameter is provided by userland (hence the __user
annotation) but for x32 syscalls it's simply cast to a kernel pointer
and is passed to __sys_recvmmsg which will eventually directly
dereference it for both reading and writing. Other callers to
__sys_recvmmsg properly copy from userland to the kernel first.
The bug was introduced by commit ee4fa23c4bfc ("compat: Use
COMPAT_USE_64BIT_TIME in net/compat.c") and should affect all kernels
since 3.4 (and perhaps vendor kernels if they backported x32 support
along with this code).
Note that CONFIG_X86_X32_ABI gets enabled at build time and only if
CONFIG_X86_X32 is enabled and ld can build x32 executables.
Other uses of COMPAT_USE_64BIT_TIME seem fine.
This addresses CVE-2014-0038.
Signed-off-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.4+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
net/compat.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/net/compat.c b/net/compat.c
index dd32e34..f50161f 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -780,21 +780,16 @@ asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
if (flags & MSG_CMSG_COMPAT)
return -EINVAL;
- if (COMPAT_USE_64BIT_TIME)
- return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
- flags | MSG_CMSG_COMPAT,
- (struct timespec *) timeout);
-
if (timeout == NULL)
return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
flags | MSG_CMSG_COMPAT, NULL);
- if (get_compat_timespec(&ktspec, timeout))
+ if (compat_get_timespec(&ktspec, timeout))
return -EFAULT;
datagrams = __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
flags | MSG_CMSG_COMPAT, &ktspec);
- if (datagrams > 0 && put_compat_timespec(&ktspec, timeout))
+ if (datagrams > 0 && compat_put_timespec(&ktspec, timeout))
datagrams = -EFAULT;
return datagrams;
--
1.8.5.3
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