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resolv: Always set *resplen2 out parameter in send_vc [BZ #19825] 

In various error scenarios (for example, if the server closes the
TCP connection before sending the full response), send_vc can return
without resetting the *resplen2 value.  This can pass uninitialized
or unexpected data to the caller.
This commit is contained in:
Florian Weimer 2016-04-27 14:26:47 +02:00
parent b06549a5e6
commit b9bdfa7c8f
2 changed files with 25 additions and 21 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
2016-04-27 Florian Weimer <fweimer@redhat.com>
[BZ #19825]
* resolv/res_send.c (send_vc): Remove early *resplen2
initialization. Set *resplen2 on socket error. Call
close_and_return_error for other errors.
2016-04-27 Stefan Liebler <stli@linux.vnet.ibm.com>
* sysdeps/unix/sysv/linux/netiucv/iucv.h

39
resolv/res_send.c
View File

@ -762,8 +762,6 @@ send_vc(res_state statp,
u_short len2;
u_char *cp;
if (resplen2 != NULL)
*resplen2 = 0;
connreset = 0;
same_ns:
truncating = 0;
@ -789,6 +787,8 @@ send_vc(res_state statp,
if (statp->_vcsock < 0) {
*terrno = errno;
Perror(statp, stderr, "socket(vc)", errno);
if (resplen2 != NULL)
*resplen2 = 0;
return (-1);
}
__set_errno (0);
@ -798,8 +798,7 @@ send_vc(res_state statp,
: sizeof (struct sockaddr_in6)) < 0) {
*terrno = errno;
Aerror(statp, stderr, "connect/vc", errno, nsap);
__res_iclose(statp, false);
return (0);
return close_and_return_error (statp, resplen2);
}
statp->_flags |= RES_F_VC;
}
@ -822,8 +821,7 @@ send_vc(res_state statp,
if (TEMP_FAILURE_RETRY (writev(statp->_vcsock, iov, niov)) != explen) {
*terrno = errno;
Perror(statp, stderr, "write failed", errno);
__res_iclose(statp, false);
return (0);
return close_and_return_error (statp, resplen2);
}
/*
* Receive length & response
@ -845,7 +843,6 @@ send_vc(res_state statp,
if (n <= 0) {
*terrno = errno;
Perror(statp, stderr, "read failed", errno);
__res_iclose(statp, false);
/*
* A long running process might get its TCP
* connection reset if the remote server was
@ -855,11 +852,13 @@ send_vc(res_state statp,
* instead of failing. We only allow one reset
* per query to prevent looping.
*/
if (*terrno == ECONNRESET && !connreset) {
connreset = 1;
goto same_ns;
}
return (0);
if (*terrno == ECONNRESET && !connreset)
{
__res_iclose (statp, false);
connreset = 1;
goto same_ns;
}
return close_and_return_error (statp, resplen2);
}
int rlen = ntohs (rlen16);
@ -891,11 +890,11 @@ send_vc(res_state statp,
/* Always allocate MAXPACKET, callers expect
this specific size. */
u_char *newp = malloc (MAXPACKET);
if (newp == NULL) {
*terrno = ENOMEM;
__res_iclose(statp, false);
return (0);
}
if (newp == NULL)
{
*terrno = ENOMEM;
return close_and_return_error (statp, resplen2);
}
*thisanssizp = MAXPACKET;
*thisansp = newp;
if (thisansp == ansp2)
@ -922,8 +921,7 @@ send_vc(res_state statp,
Dprint(statp->options & RES_DEBUG,
(stdout, ";; undersized: %d\n", len));
*terrno = EMSGSIZE;
__res_iclose(statp, false);
return (0);
return close_and_return_error (statp, resplen2);
}
cp = *thisansp;
@ -934,8 +932,7 @@ send_vc(res_state statp,
if (__glibc_unlikely (n <= 0)) {
*terrno = errno;
Perror(statp, stderr, "read(vc)", errno);
__res_iclose(statp, false);
return (0);
return close_and_return_error (statp, resplen2);
}
if (__glibc_unlikely (truncating)) {
/*