[Qemu-devel] [PATCH v5 01/10] linux-user/syscall: Verify recvfrom(addr) is user-writable

[Laurent Vivier]

On 11/10/2018 00:36, Philippe Mathieu-Daudé wrote:
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> Tested-By: Guido Günther <address@hidden>
> Reviewed-by: Laurent Vivier <address@hidden>
> ---
>  linux-user/syscall.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index ae3c0dfef7..ea503381aa 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -2968,6 +2968,11 @@ static abi_long do_recvfrom(int fd, abi_ulong msg, 
> size_t len, int flags,
>              ret = -TARGET_EINVAL;
>              goto fail;
>          }
> +        if (!access_ok(VERIFY_WRITE, target_addr, addrlen)) {
> +            ret = -TARGET_EFAULT;
> +            goto fail;
> +        }
> +
>          addr = alloca(addrlen);
>          ret = get_errno(safe_recvfrom(fd, host_msg, len, flags,
>                                        addr, &addrlen));
> 

This one breaks the test recvfrom01 from the LTP testsuite
ltp-full-20180515 archive.

recvfrom01    3  TFAIL  :  recvfrom01.c:170: invalid socket buffer ;
returned -1 (expected 0), errno 14 (expected 88)

The testcase is with an invalid socket number (-1) and an invalid
addrlen pointer.

Thanks,
Laurent