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linux-user: Handle short lengths in host_to_target_sockaddr()

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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>
This commit is contained in:
Peter Maydell 2016-07-07 15:44:43 +01:00 committed by Riku Voipio
parent 31efaef1d9
commit a1e221929f
1 changed files with 9 additions and 2 deletions
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11
linux-user/syscall.c
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@ -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);