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unix: ensure struct msghdr is zeroed in recvmmsg (#3419)

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With MUSL libc, the struct msghdr is padded to align with the types used
in the Linux kernel headers (int vs size_t).  When the padding was not
zeroed, the syscall would return EMSGSIZE because the random bytes in
the padding would be read by kernel as part of the size_t type.

Fixes: https://github.com/libuv/libuv/issues/3416
This commit is contained in:
Ondřej Surý 2022-01-15 06:24:37 +01:00 committed by Ben Noordhuis
parent 2fbfa0358b
commit e9cb18484e
1 changed files with 6 additions and 5 deletions
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11
src/unix/udp.c
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@ -201,6 +201,7 @@ static int uv__udp_recvmmsg(uv_udp_t* handle, uv_buf_t* buf) {
for (k = 0; k < chunks; ++k) {
iov[k].iov_base = buf->base + k * UV__UDP_DGRAM_MAXSIZE;
iov[k].iov_len = UV__UDP_DGRAM_MAXSIZE;
memset(&msgs[k].msg_hdr, 0, sizeof(msgs[k].msg_hdr));
msgs[k].msg_hdr.msg_iov = iov + k;
msgs[k].msg_hdr.msg_iovlen = 1;
msgs[k].msg_hdr.msg_name = peers + k;
@ -655,16 +656,16 @@ int uv__udp_connect(uv_udp_t* handle,
}
/* From https://pubs.opengroup.org/onlinepubs/9699919799/functions/connect.html
* Any of uv supported UNIXs kernel should be standardized, but the kernel
* Any of uv supported UNIXs kernel should be standardized, but the kernel
* implementation logic not same, let's use pseudocode to explain the udp
* disconnect behaviors:
*
*
* Predefined stubs for pseudocode:
* 1. sodisconnect: The function to perform the real udp disconnect
* 2. pru_connect: The function to perform the real udp connect
* 3. so: The kernel object match with socket fd
* 4. addr: The sockaddr parameter from user space
*
*
* BSDs:
* if(sodisconnect(so) == 0) { // udp disconnect succeed
* if (addr->sa_len != so->addr->sa_len) return EINVAL;
@ -694,13 +695,13 @@ int uv__udp_disconnect(uv_udp_t* handle) {
#endif
memset(&addr, 0, sizeof(addr));
#if defined(__MVS__)
addr.ss_family = AF_UNSPEC;
#else
addr.sa_family = AF_UNSPEC;
#endif
do {
errno = 0;
r = connect(handle->io_watcher.fd, (struct sockaddr*) &addr, sizeof(addr));