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linux: Fix ancillary 64-bit time timestamp conversion (BZ #28349, BZ #28350)

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The __convert_scm_timestamps() only updates the control message last
pointer for SOL_SOCKET type, so if the message control buffer contains
multiple ancillary message types the converted timestamp one might
overwrite a valid message.

The test check if the extra ancillary space is correctly handled
by recvmsg/recvmmsg, where if there is no extra space for the 64-bit
time_t converted message the control buffer should be marked with
MSG_TRUNC.  It also check if recvmsg/recvmmsg handle correctly multiple
ancillary data.

Checked on x86_64-linux and on i686-linux-gnu on both 5.11 and
4.15 kernel.

Co-authored-by: Fabian Vogt <fvogt@suse.de>
This commit is contained in:
Adhemerval Zanella
2021-09-27 16:07:08 -03:00
parent a4cf12360f
commit 21e0f45c7d
4 changed files with 354 additions and 5 deletions
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11
sysdeps/unix/sysv/linux/convert_scm_timestamps.c
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@@ -54,6 +54,8 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
cmsg != NULL;
cmsg = CMSG_NXTHDR (msg, cmsg))
{
last = cmsg;
if (cmsg->cmsg_level != SOL_SOCKET)
continue;
@@ -75,8 +77,6 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
tvts[1] = tmp[1];
break;
}
last = cmsg;
}
if (last == NULL || type == 0)
@@ -88,10 +88,11 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
return;
}
/* Zero memory for the new cmsghdr, required by CMSG_NXTHDR. */
memset (msg->msg_control + msg->msg_controllen, 0,
CMSG_SPACE (sizeof tvts));
msg->msg_controllen += CMSG_SPACE (sizeof tvts);
cmsg = CMSG_NXTHDR(msg, last);
if (cmsg == NULL)
return;
cmsg = CMSG_NXTHDR (msg, last);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = type;
cmsg->cmsg_len = CMSG_LEN (sizeof tvts);