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reds-stream: Don't use sendmsg with uninitialized memory

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On my 64 bit Fedora 25, CMSG_SPACE() adds 4 bytes of padding after the
file descriptor in the control data. This causes warnings when ran under
valgrind as we set msg_controllen to CMSG_SPACE().

This commit fills the control data to 0 to avoid these warnings.

==30301== Syscall param sendmsg(msg.msg_control) points to uninitialised byte(s)
==30301==    at 0x8127367: sendmsg (sendmsg.c:28)
==30301==    by 0x41880B: reds_stream_send_msgfd (reds-stream.c:295)
==30301==    by 0x40953F: main (test-stream.c:121)
==30301==  Address 0xffefff1b4 is on thread 1's stack
==30301==  in frame #1, created by reds_stream_send_msgfd (reds-stream.c:263)

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
Acked-by: Pavel Grunt <pgrunt@redhat.com>
This commit is contained in:
Christophe Fergeau 2017-03-14 15:41:38 +01:00
parent a0c32918a2
commit 8be1120904
1 changed files with 4 additions and 0 deletions
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4
server/reds-stream.c
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@ -283,6 +283,10 @@ int reds_stream_send_msgfd(RedsStream *stream, int fd)
if (fd != -1) {
msgh.msg_control = control.data;
msgh.msg_controllen = sizeof(control.data);
/* CMSG_SPACE() might be larger than CMSG_LEN() as it can include some
* padding. We set the whole control data to 0 to avoid valgrind warnings
*/
memset(control.data, 0, sizeof(control.data));
cmsg = CMSG_FIRSTHDR(&msgh);
cmsg->cmsg_len = CMSG_LEN(fd_size);