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

1 files changed, 45 insertions, 0 deletions

diff --git a/toolchain/uClibc/patches-0.9.30.3/902-Fix-use-after-free-bug-in-__dns_lookup.patch b/toolchain/uClibc/patches-0.9.30.3/902-Fix-use-after-free-bug-in-__dns_lookup.patch
new file mode 100644
index 0000000000..3a6f43d340
--- /dev/null
+++ b/toolchain/uClibc/patches-0.9.30.3/902-Fix-use-after-free-bug-in-__dns_lookup.patch
@@ -0,0 +1,45 @@
+From c602079e5b7ba998d1dd6cae4a305af80e6cba52 Mon Sep 17 00:00:00 2001
+From: Gabor Juhos <juhosg@openwrt.org>
+Date: Tue, 23 Mar 2010 08:35:27 +0100
+Subject: [PATCH] Fix use-after-free bug in __dns_lookup.
+
+If the type of the first answer does not match with the requested type,
+then the dotted name will be freed. If there are no further answers in
+the DNS reply, this pointer will be used later on in the same function.
+Additionally it is passed to the caller, and may cause strange behaviour.
+
+For example, the following busybox commands are triggering a segmentation
+fault with uClibc 0.9.30.x
+
+  - nslookup ipv6.google.com
+  - ping ipv6.google.com
+  - wget http//ipv6.google.com/
+
+Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
+
+---
+
+See https://dev.openwrt.org/ticket/6886 for a testcase
+---
+ libc/inet/resolv.c |    4 +---
+ 1 files changed, 1 insertions(+), 3 deletions(-)
+
+diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
+index 0a6fd7a..e76f0aa 100644
+--- a/libc/inet/resolv.c
++++ b/libc/inet/resolv.c
+@@ -1501,10 +1501,8 @@ int attribute_hidden __dns_lookup(const char *name,
+ 				memcpy(a, &ma, sizeof(ma));
+ 				if (a->atype != T_SIG && (NULL == a->buf || (type != T_A && type != T_AAAA)))
+ 					break;
+-				if (a->atype != type) {
+-					free(a->dotted);
++				if (a->atype != type)
+ 					continue;
+-				}
+ 				a->add_count = h.ancount - j - 1;
+ 				if ((a->rdlength + sizeof(struct in_addr*)) * a->add_count > a->buflen)
+ 					break;
+-- 
+1.5.3.2
+