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Infinite loop in res_mkquery with malformed domain name (#2255506)

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This commit is contained in:
Florian Weimer 2024-01-03 16:42:48 +01:00
parent ca9e6ac795
commit d6f60005eb
2 changed files with 144 additions and 1 deletions
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139
glibc-rh2255506.patch Normal file
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@ -0,0 +1,139 @@
commit 3e0853ab9a1609707ec8de453891b3c79ea556bc
Author: Florian Weimer <fweimer@redhat.com>
Date: Wed Jan 3 16:40:32 2024 +0100
Revert "resolve: Remove __res_context_query alloca usage"
This reverts commit 40c0add7d48739f5d89ebba255c1df26629a76e2.
The change causes an infinite loop with malformed domain
names.
diff --git a/resolv/res_query.c b/resolv/res_query.c
index 1b148a2a05b8641c..049de91b95a2bd0c 100644
--- a/resolv/res_query.c
+++ b/resolv/res_query.c
@@ -80,7 +80,6 @@
#include <stdlib.h>
#include <string.h>
#include <shlib-compat.h>
-#include <scratch_buffer.h>
#if PACKETSZ > 65536
#define MAXPACKET PACKETSZ
@@ -115,14 +114,11 @@ __res_context_query (struct resolv_context *ctx, const char *name,
struct __res_state *statp = ctx->resp;
UHEADER *hp = (UHEADER *) answer;
UHEADER *hp2;
- int n;
-
- /* It requires 2 times QUERYSIZE for type == T_QUERY_A_AND_AAAA. */
- struct scratch_buffer buf;
- scratch_buffer_init (&buf);
- _Static_assert (2 * QUERYSIZE <= sizeof (buf.__space.__c),
- "scratch_buffer too small");
- u_char *query1 = buf.data;
+ int n, use_malloc = 0;
+
+ size_t bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * QUERYSIZE;
+ u_char *buf = alloca (bufsize);
+ u_char *query1 = buf;
int nquery1 = -1;
u_char *query2 = NULL;
int nquery2 = 0;
@@ -133,28 +129,37 @@ __res_context_query (struct resolv_context *ctx, const char *name,
if (type == T_QUERY_A_AND_AAAA)
{
n = __res_context_mkquery (ctx, QUERY, name, class, T_A, NULL,
- query1, buf.length);
+ query1, bufsize);
if (n > 0)
{
if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
{
/* Use RESOLV_EDNS_BUFFER_SIZE because the receive
buffer can be reallocated. */
- n = __res_nopt (ctx, n, query1, buf.length,
+ n = __res_nopt (ctx, n, query1, bufsize,
RESOLV_EDNS_BUFFER_SIZE);
if (n < 0)
goto unspec_nomem;
}
nquery1 = n;
- query2 = buf.data + n;
+ /* Align the buffer. */
+ int npad = ((nquery1 + __alignof__ (HEADER) - 1)
+ & ~(__alignof__ (HEADER) - 1)) - nquery1;
+ if (n > bufsize - npad)
+ {
+ n = -1;
+ goto unspec_nomem;
+ }
+ int nused = n + npad;
+ query2 = buf + nused;
n = __res_context_mkquery (ctx, QUERY, name, class, T_AAAA,
- NULL, query2, buf.length - n);
+ NULL, query2, bufsize - nused);
if (n > 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
/* Use RESOLV_EDNS_BUFFER_SIZE because the receive
buffer can be reallocated. */
- n = __res_nopt (ctx, n, query2, buf.length,
+ n = __res_nopt (ctx, n, query2, bufsize,
RESOLV_EDNS_BUFFER_SIZE);
nquery2 = n;
}
@@ -164,7 +169,7 @@ __res_context_query (struct resolv_context *ctx, const char *name,
else
{
n = __res_context_mkquery (ctx, QUERY, name, class, type, NULL,
- query1, buf.length);
+ query1, bufsize);
if (n > 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
@@ -176,25 +181,27 @@ __res_context_query (struct resolv_context *ctx, const char *name,
advertise = anslen;
else
advertise = RESOLV_EDNS_BUFFER_SIZE;
- n = __res_nopt (ctx, n, query1, buf.length, advertise);
+ n = __res_nopt (ctx, n, query1, bufsize, advertise);
}
nquery1 = n;
}
- if (__glibc_unlikely (n <= 0)) {
+ if (__glibc_unlikely (n <= 0) && !use_malloc) {
/* Retry just in case res_nmkquery failed because of too
short buffer. Shouldn't happen. */
- if (scratch_buffer_set_array_size (&buf,
- T_QUERY_A_AND_AAAA ? 2 : 1,
- MAXPACKET)) {
- query1 = buf.data;
+ bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * MAXPACKET;
+ buf = malloc (bufsize);
+ if (buf != NULL) {
+ query1 = buf;
+ use_malloc = 1;
goto again;
}
}
if (__glibc_unlikely (n <= 0)) {
RES_SET_H_ERRNO(statp, NO_RECOVERY);
- scratch_buffer_free (&buf);
+ if (use_malloc)
+ free (buf);
return (n);
}
@@ -217,7 +224,8 @@ __res_context_query (struct resolv_context *ctx, const char *name,
answerp2_malloced);
}
- scratch_buffer_free (&buf);
+ if (use_malloc)
+ free (buf);
if (n < 0) {
RES_SET_H_ERRNO(statp, TRY_AGAIN);
return (n);

6
glibc.spec
View File

@ -171,7 +171,7 @@ Version: %{glibcversion}
# - It allows using the Release number without the %%dist tag in the dependency
# generator to make the generated requires interchangeable between Rawhide
# and ELN (.elnYY < .fcXX).
%global baserelease 29
%global baserelease 30
Release: %{baserelease}%{?dist}
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
@ -242,6 +242,7 @@ Patch9: glibc-rh827510.patch
Patch13: glibc-fedora-localedata-rh61908.patch
Patch17: glibc-cs-path.patch
Patch23: glibc-python3.patch
Patch24: glibc-rh2255506.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -2212,6 +2213,9 @@ update_gconv_modules_cache ()
%files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
%changelog
* Wed Jan 3 2024 Florian Weimer <fweimer@redhat.com> - 2.38.9000-30
- Infinite loop in res_mkquery with malformed domain name (#2255506)
* Fri Dec 22 2023 Florian Weimer <fweimer@redhat.com> - 2.38.9000-29
- Auto-sync with upstream branch master,
commit 61bac1a9d2ab80ebcbc51484722e6ea43414bec7: