Commit a1e22192 authored Jul 07, 2016 by Peter Maydell Committed by Riku Voipio Jul 19, 2016

linux-user: Handle short lengths in host_to_target_sockaddr()



If userspace specifies a short buffer for a target sockaddr,
the kernel will only copy in as much as it has space for
(or none at all if the length is zero) -- see the kernel
move_addr_to_user() function. Mimic this in QEMU's
host_to_target_sockaddr() routine.

In particular, this fixes a segfault running the LTP
recvfrom01 test, where the guest makes a recvfrom()
call with a bad buffer pointer and other parameters which
cause the kernel to set the addrlen to zero; because we
did not skip the attempt to swap the sa_family field we
segfaulted on the bad address.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

parent 31efaef1

linux-user/syscall.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -1376,12 +1376,19 @@ static inline abi_long host_to_target_sockaddr(abi_ulong target_addr,
		{
		struct target_sockaddr *target_saddr;

		if (len == 0) {
		return 0;
		}

		target_saddr = lock_user(VERIFY_WRITE, target_addr, len, 0);
		if (!target_saddr)
		return -TARGET_EFAULT;
		memcpy(target_saddr, addr, len);
		if (len >= offsetof(struct target_sockaddr, sa_family) +
		sizeof(target_saddr->sa_family)) {
		target_saddr->sa_family = tswap16(addr->sa_family);
		if (addr->sa_family == AF_NETLINK) {
		}
		if (addr->sa_family == AF_NETLINK && len >= sizeof(struct sockaddr_nl)) {
		struct sockaddr_nl target_nl = (struct sockaddr_nl )target_saddr;
		target_nl->nl_pid = tswap32(target_nl->nl_pid);
		target_nl->nl_groups = tswap32(target_nl->nl_groups);