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uClibc: fix free-after-use bug in __dns_lookup (closes #6886)
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20384 3c298f89-4303-0410-b956-a3cf2f4a3e73
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juhosg
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From c602079e5b7ba998d1dd6cae4a305af80e6cba52 Mon Sep 17 00:00:00 2001
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From: Gabor Juhos <juhosg@openwrt.org>
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Date: Tue, 23 Mar 2010 08:35:27 +0100
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Subject: [PATCH] Fix use-after-free bug in __dns_lookup.
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If the type of the first answer does not match with the requested type,
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then the dotted name will be freed. If there are no further answers in
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the DNS reply, this pointer will be used later on in the same function.
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Additionally it is passed to the caller, and may cause strange behaviour.
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For example, the following busybox commands are triggering a segmentation
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fault with uClibc 0.9.30.x
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- nslookup ipv6.google.com
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- ping ipv6.google.com
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- wget http//ipv6.google.com/
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Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
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---
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See https://dev.openwrt.org/ticket/6886 for a testcase
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---
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libc/inet/resolv.c | 4 +---
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1 files changed, 1 insertions(+), 3 deletions(-)
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diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
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index 0a6fd7a..e76f0aa 100644
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--- a/libc/inet/resolv.c
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+++ b/libc/inet/resolv.c
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@@ -1501,10 +1501,8 @@ int attribute_hidden __dns_lookup(const char *name,
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memcpy(a, &ma, sizeof(ma));
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if (a->atype != T_SIG && (NULL == a->buf || (type != T_A && type != T_AAAA)))
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break;
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- if (a->atype != type) {
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- free(a->dotted);
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+ if (a->atype != type)
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continue;
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- }
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a->add_count = h.ancount - j - 1;
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if ((a->rdlength + sizeof(struct in_addr*)) * a->add_count > a->buflen)
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break;
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--
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1.5.3.2
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@ -0,0 +1,45 @@
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From c602079e5b7ba998d1dd6cae4a305af80e6cba52 Mon Sep 17 00:00:00 2001
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From: Gabor Juhos <juhosg@openwrt.org>
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Date: Tue, 23 Mar 2010 08:35:27 +0100
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Subject: [PATCH] Fix use-after-free bug in __dns_lookup.
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If the type of the first answer does not match with the requested type,
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then the dotted name will be freed. If there are no further answers in
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the DNS reply, this pointer will be used later on in the same function.
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Additionally it is passed to the caller, and may cause strange behaviour.
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For example, the following busybox commands are triggering a segmentation
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fault with uClibc 0.9.30.x
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- nslookup ipv6.google.com
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- ping ipv6.google.com
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- wget http//ipv6.google.com/
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Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
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---
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See https://dev.openwrt.org/ticket/6886 for a testcase
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---
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libc/inet/resolv.c | 4 +---
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1 files changed, 1 insertions(+), 3 deletions(-)
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diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
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index 0a6fd7a..e76f0aa 100644
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--- a/libc/inet/resolv.c
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+++ b/libc/inet/resolv.c
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@@ -1501,10 +1501,8 @@ int attribute_hidden __dns_lookup(const char *name,
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memcpy(a, &ma, sizeof(ma));
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if (a->atype != T_SIG && (NULL == a->buf || (type != T_A && type != T_AAAA)))
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break;
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- if (a->atype != type) {
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- free(a->dotted);
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+ if (a->atype != type)
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continue;
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- }
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a->add_count = h.ancount - j - 1;
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if ((a->rdlength + sizeof(struct in_addr*)) * a->add_count > a->buflen)
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break;
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--
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1.5.3.2
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@ -0,0 +1,45 @@
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From c602079e5b7ba998d1dd6cae4a305af80e6cba52 Mon Sep 17 00:00:00 2001
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From: Gabor Juhos <juhosg@openwrt.org>
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Date: Tue, 23 Mar 2010 08:35:27 +0100
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Subject: [PATCH] Fix use-after-free bug in __dns_lookup.
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If the type of the first answer does not match with the requested type,
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then the dotted name will be freed. If there are no further answers in
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the DNS reply, this pointer will be used later on in the same function.
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Additionally it is passed to the caller, and may cause strange behaviour.
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For example, the following busybox commands are triggering a segmentation
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fault with uClibc 0.9.30.x
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- nslookup ipv6.google.com
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- ping ipv6.google.com
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- wget http//ipv6.google.com/
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Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
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---
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See https://dev.openwrt.org/ticket/6886 for a testcase
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---
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libc/inet/resolv.c | 4 +---
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1 files changed, 1 insertions(+), 3 deletions(-)
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diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
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index 0a6fd7a..e76f0aa 100644
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--- a/libc/inet/resolv.c
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+++ b/libc/inet/resolv.c
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@@ -1501,10 +1501,8 @@ int attribute_hidden __dns_lookup(const char *name,
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memcpy(a, &ma, sizeof(ma));
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if (a->atype != T_SIG && (NULL == a->buf || (type != T_A && type != T_AAAA)))
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break;
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- if (a->atype != type) {
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- free(a->dotted);
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+ if (a->atype != type)
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continue;
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- }
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a->add_count = h.ancount - j - 1;
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if ((a->rdlength + sizeof(struct in_addr*)) * a->add_count > a->buflen)
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break;
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--
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1.5.3.2
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