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Fetched from gentoo glibc patchball
Original patch filename: 10_all_glibc-CVE-2015-7547.patch
Based on: https://sourceware.org/ml/libc-alpha/2016-02/msg00416.html
Fixes:
CVE-2015-7547 - glibc getaddrinfo stack-based buffer overflow.
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -1031,7 +1031,10 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
int h_namelen = 0;
if (ancount == 0)
- return NSS_STATUS_NOTFOUND;
+ {
+ *h_errnop = HOST_NOT_FOUND;
+ return NSS_STATUS_NOTFOUND;
+ }
while (ancount-- > 0 && cp < end_of_message && had_error == 0)
{
@@ -1208,7 +1211,14 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
/* Special case here: if the resolver sent a result but it only
contains a CNAME while we are looking for a T_A or T_AAAA record,
we fail with NOTFOUND instead of TRYAGAIN. */
- return canon == NULL ? NSS_STATUS_TRYAGAIN : NSS_STATUS_NOTFOUND;
+ if (canon != NULL)
+ {
+ *h_errnop = HOST_NOT_FOUND;
+ return NSS_STATUS_NOTFOUND;
+ }
+
+ *h_errnop = NETDB_INTERNAL;
+ return NSS_STATUS_TRYAGAIN;
}
@@ -1242,8 +1252,15 @@ gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2,
&pat, &buffer, &buflen,
errnop, h_errnop, ttlp,
&first);
+ /* Use the second response status in some cases. */
if (status != NSS_STATUS_SUCCESS && status2 != NSS_STATUS_NOTFOUND)
status = status2;
+ /* Do not return a truncated second response (unless it was
+ unavoidable e.g. unrecoverable TRYAGAIN). */
+ if (status == NSS_STATUS_SUCCESS
+ && (status2 == NSS_STATUS_TRYAGAIN
+ && *errnop == ERANGE && *h_errnop != NO_RECOVERY))
+ status = NSS_STATUS_TRYAGAIN;
}
return status;
--- a/resolv/res_query.c
+++ b/resolv/res_query.c
@@ -396,6 +396,7 @@ __libc_res_nsearch(res_state statp,
{
free (*answerp2);
*answerp2 = NULL;
+ *nanswerp2 = 0;
*answerp2_malloced = 0;
}
}
@@ -447,6 +448,7 @@ __libc_res_nsearch(res_state statp,
{
free (*answerp2);
*answerp2 = NULL;
+ *nanswerp2 = 0;
*answerp2_malloced = 0;
}
@@ -521,6 +523,7 @@ __libc_res_nsearch(res_state statp,
{
free (*answerp2);
*answerp2 = NULL;
+ *nanswerp2 = 0;
*answerp2_malloced = 0;
}
if (saved_herrno != -1)
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -639,11 +639,7 @@ send_vc(res_state statp,
{
const HEADER *hp = (HEADER *) buf;
const HEADER *hp2 = (HEADER *) buf2;
- u_char *ans = *ansp;
- int orig_anssizp = *anssizp;
- // XXX REMOVE
- // int anssiz = *anssizp;
- HEADER *anhp = (HEADER *) ans;
+ HEADER *anhp = (HEADER *) *ansp;
struct sockaddr *nsap = get_nsaddr (statp, ns);
int truncating, connreset, n;
/* On some architectures compiler might emit a warning indicating
@@ -767,35 +763,6 @@ send_vc(res_state statp,
assert (anscp != NULL || ansp2 == NULL);
thisresplenp = &resplen;
} else {
- if (*anssizp != MAXPACKET) {
- /* No buffer allocated for the first
- reply. We can try to use the rest
- of the user-provided buffer. */
-#if __GNUC_PREREQ (4, 7)
- DIAG_PUSH_NEEDS_COMMENT;
- DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
-#endif
-#if _STRING_ARCH_unaligned
- *anssizp2 = orig_anssizp - resplen;
- *ansp2 = *ansp + resplen;
-#else
- int aligned_resplen
- = ((resplen + __alignof__ (HEADER) - 1)
- & ~(__alignof__ (HEADER) - 1));
- *anssizp2 = orig_anssizp - aligned_resplen;
- *ansp2 = *ansp + aligned_resplen;
-#endif
-#if __GNUC_PREREQ (4, 7)
- DIAG_POP_NEEDS_COMMENT;
-#endif
- } else {
- /* The first reply did not fit into the
- user-provided buffer. Maybe the second
- answer will. */
- *anssizp2 = orig_anssizp;
- *ansp2 = *ansp;
- }
-
thisanssizp = anssizp2;
thisansp = ansp2;
thisresplenp = resplen2;
@@ -804,10 +771,14 @@ send_vc(res_state statp,
anhp = (HEADER *) *thisansp;
*thisresplenp = rlen;
- if (rlen > *thisanssizp) {
- /* Yes, we test ANSCP here. If we have two buffers
- both will be allocatable. */
- if (__glibc_likely (anscp != NULL)) {
+ /* Is the answer buffer too small? */
+ if (*thisanssizp < rlen) {
+ /* If the current buffer is not the the static
+ user-supplied buffer then we can reallocate
+ it. */
+ if (thisansp != NULL && thisansp != ansp) {
+ /* Always allocate MAXPACKET, callers expect
+ this specific size. */
u_char *newp = malloc (MAXPACKET);
if (newp == NULL) {
*terrno = ENOMEM;
@@ -957,8 +928,6 @@ send_dg(res_state statp,
{
const HEADER *hp = (HEADER *) buf;
const HEADER *hp2 = (HEADER *) buf2;
- u_char *ans = *ansp;
- int orig_anssizp = *anssizp;
struct timespec now, timeout, finish;
struct pollfd pfd[1];
int ptimeout;
@@ -1154,50 +1123,48 @@ send_dg(res_state statp,
assert (anscp != NULL || ansp2 == NULL);
thisresplenp = &resplen;
} else {
- if (*anssizp != MAXPACKET) {
- /* No buffer allocated for the first
- reply. We can try to use the rest
- of the user-provided buffer. */
-#if _STRING_ARCH_unaligned
- *anssizp2 = orig_anssizp - resplen;
- *ansp2 = *ansp + resplen;
-#else
- int aligned_resplen
- = ((resplen + __alignof__ (HEADER) - 1)
- & ~(__alignof__ (HEADER) - 1));
- *anssizp2 = orig_anssizp - aligned_resplen;
- *ansp2 = *ansp + aligned_resplen;
-#endif
- } else {
- /* The first reply did not fit into the
- user-provided buffer. Maybe the second
- answer will. */
- *anssizp2 = orig_anssizp;
- *ansp2 = *ansp;
- }
-
thisanssizp = anssizp2;
thisansp = ansp2;
thisresplenp = resplen2;
}
if (*thisanssizp < MAXPACKET
- /* Yes, we test ANSCP here. If we have two buffers
- both will be allocatable. */
- && anscp
+ /* If the current buffer is not the the static
+ user-supplied buffer then we can reallocate
+ it. */
+ && (thisansp != NULL && thisansp != ansp)
#ifdef FIONREAD
+ /* Is the size too small? */
&& (ioctl (pfd[0].fd, FIONREAD, thisresplenp) < 0
|| *thisanssizp < *thisresplenp)
#endif
) {
+ /* Always allocate MAXPACKET, callers expect
+ this specific size. */
u_char *newp = malloc (MAXPACKET);
if (newp != NULL) {
- *anssizp = MAXPACKET;
- *thisansp = ans = newp;
+ *thisanssizp = MAXPACKET;
+ *thisansp = newp;
if (thisansp == ansp2)
*ansp2_malloced = 1;
}
}
+ /* We could end up with truncation if anscp was NULL
+ (not allowed to change caller's buffer) and the
+ response buffer size is too small. This isn't a
+ reliable way to detect truncation because the ioctl
+ may be an inaccurate report of the UDP message size.
+ Therefore we use this only to issue debug output.
+ To do truncation accurately with UDP we need
+ MSG_TRUNC which is only available on Linux. We
+ can abstract out the Linux-specific feature in the
+ future to detect truncation. */
+ if (__glibc_unlikely (*thisanssizp < *thisresplenp)) {
+ Dprint(statp->options & RES_DEBUG,
+ (stdout, ";; response may be truncated (UDP)
")
+ );
+ }
+
HEADER *anhp = (HEADER *) *thisansp;
socklen_t fromlen = sizeof(struct sockaddr_in6);
assert (sizeof(from) <= fromlen);
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