65 lines
2.4 KiB
Diff
65 lines
2.4 KiB
Diff
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From 9903253c347f9e0bffd285ae3829aef251cc852d Mon Sep 17 00:00:00 2001
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From: hopper-vul <118949689+hopper-vul@users.noreply.github.com>
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Date: Wed, 18 Jan 2023 22:14:26 +0800
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Subject: [PATCH] Add str len check in config_sortlist to avoid stack overflow
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(#497)
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In ares_set_sortlist, it calls config_sortlist(..., sortstr) to parse
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the input str and initialize a sortlist configuration.
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However, ares_set_sortlist has not any checks about the validity of the input str.
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It is very easy to create an arbitrary length stack overflow with the unchecked
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`memcpy(ipbuf, str, q-str);` and `memcpy(ipbufpfx, str, q-str);`
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statements in the config_sortlist call, which could potentially cause severe
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security impact in practical programs.
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This commit add necessary check for `ipbuf` and `ipbufpfx` which avoid the
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potential stack overflows.
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fixes #496
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Fix By: @hopper-vul
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---
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ares_init.c | 4 ++++
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test/ares-test-init.cc | 2 ++
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2 files changed, 6 insertions(+)
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diff --git a/ares_init.c b/ares_init.c
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index f7b700b..5aad7c8 100644
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--- a/ares_init.c
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+++ b/ares_init.c
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@@ -2065,6 +2065,8 @@ static int config_sortlist(struct apattern **sortlist, int *nsort,
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q = str;
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while (*q && *q != '/' && *q != ';' && !ISSPACE(*q))
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q++;
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+ if (q-str >= 16)
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+ return ARES_EBADSTR;
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memcpy(ipbuf, str, q-str);
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ipbuf[q-str] = '\0';
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/* Find the prefix */
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@@ -2073,6 +2075,8 @@ static int config_sortlist(struct apattern **sortlist, int *nsort,
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const char *str2 = q+1;
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while (*q && *q != ';' && !ISSPACE(*q))
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q++;
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+ if (q-str >= 32)
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+ return ARES_EBADSTR;
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memcpy(ipbufpfx, str, q-str);
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ipbufpfx[q-str] = '\0';
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str = str2;
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diff --git a/test/ares-test-init.cc b/test/ares-test-init.cc
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index 63c6a22..ee84518 100644
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--- a/test/ares-test-init.cc
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+++ b/test/ares-test-init.cc
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@@ -275,6 +275,8 @@ TEST_F(DefaultChannelTest, SetAddresses) {
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TEST_F(DefaultChannelTest, SetSortlistFailures) {
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EXPECT_EQ(ARES_ENODATA, ares_set_sortlist(nullptr, "1.2.3.4"));
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+ EXPECT_EQ(ARES_EBADSTR, ares_set_sortlist(channel_, "111.111.111.111*/16"));
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+ EXPECT_EQ(ARES_EBADSTR, ares_set_sortlist(channel_, "111.111.111.111/255.255.255.240*"));
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EXPECT_EQ(ARES_SUCCESS, ares_set_sortlist(channel_, "xyzzy ; lwk"));
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EXPECT_EQ(ARES_SUCCESS, ares_set_sortlist(channel_, "xyzzy ; 0x123"));
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}
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--
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2.37.3
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