From: "H. Peter Anvin" <[email protected]>
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
http://git.kernel.org/linus/ee4fa23c4b (other uses of
COMPAT_USE_64BIT_TIME seem fine) 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.
This addresses CVE-2014-0038.
Signed-off-by: PaX Team <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>
Cc: <[email protected]> # v3.4+
---
net/compat.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/net/compat.c b/net/compat.c
index dd32e34c1e2c..f50161fb812e 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;
--
1.8.3.1
--
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