[PATCH] linux-user: Check lock_user result for ip_mreq_source sockopts

[Peter Maydell]

In do_setsockopt(), the code path for the options which take a struct
ip_mreq_source (IP_BLOCK_SOURCE, IP_UNBLOCK_SOURCE,
IP_ADD_SOURCE_MEMBERSHIP and IP_DROP_SOURCE_MEMBERSHIP) fails to
check the return value from lock_user().  Handle this in the usual
way by returning -TARGET_EFAULT.

(In practice this was probably harmless because we'd pass a NULL
pointer to setsockopt() and the kernel would then return EFAULT.)

Fixes: Coverity CID 1459987
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
Compile-tested only; I don't have a test case to hand that
uses these socket options.

 linux-user/syscall.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ccd3892b2df..d2b062ea5a9 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2121,6 +2121,9 @@ static abi_long do_setsockopt(int sockfd, int level, int 
optname,
                 return -TARGET_EINVAL;
 
             ip_mreq_source = lock_user(VERIFY_READ, optval_addr, optlen, 1);
+            if (!ip_mreq_source) {
+                return -TARGET_EFAULT;
+            }
             ret = get_errno(setsockopt(sockfd, level, optname, ip_mreq_source, 
optlen));
             unlock_user (ip_mreq_source, optval_addr, 0);
             break;
-- 
2.20.1