| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 009/104] x86, x32: Correct invalid use of user timespec in the kernel | Date | Tue, 4 Feb 2014 13:01:12 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: PaX Team <pageexec@freemail.hu>
commit 2def2ef2ae5f3990aabdbe8a755911902707d268 upstream.
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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- net/compat.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)
--- a/net/compat.c +++ b/net/compat.c @@ -780,21 +780,16 @@ asmlinkage long compat_sys_recvmmsg(int 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;
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