From: Peter Maydell Date: Thu, 7 Jul 2016 14:44:43 +0000 (+0100) Subject: linux-user: Handle short lengths in host_to_target_sockaddr() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a1e221929f570cc84661158421f942b3328a9fd1;p=qemu.git 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 Signed-off-by: Riku Voipio --- diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 0a99af8912..ca6a2b495a 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -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); - target_saddr->sa_family = tswap16(addr->sa_family); - if (addr->sa_family == AF_NETLINK) { + 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 && 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);