diff --git a/meta-oe/recipes-support/c-ares/c-ares/CVE-2026-69186.patch b/meta-oe/recipes-support/c-ares/c-ares/CVE-2026-69186.patch new file mode 100644 index 0000000000..b3c003acaa --- /dev/null +++ b/meta-oe/recipes-support/c-ares/c-ares/CVE-2026-69186.patch @@ -0,0 +1,159 @@ +From e47c203f91cd8b749c8736bc18d75a31ffdec8f4 Mon Sep 17 00:00:00 2001 +From: jmestwa-coder +Date: Sun, 12 Apr 2026 23:50:54 +0530 +Subject: [PATCH] validate RR counts before preallocation to reject malformed + packets early (#1134) +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +## Summary + +Validate DNS RR counts before preallocation to reject malformed packets +early. + +## What’s the issue? + +The parser currently trusts RR counts from the DNS header (`ANCOUNT`, +`NSCOUNT`, `ARCOUNT`) without verifying that the packet contains enough +data. + +A malformed packet can claim a large number of records without providing +sufficient payload, causing the parser to proceed with unnecessary work +and incorrect handling. + +## What changed? + +- Added validation to ensure RR counts are feasible based on the +remaining buffer size +- Moved RR preallocation from `ares_dns_parse_header` to +`ares_dns_parse_buf` +- Perform validation after question parsing and before preallocation +- Return `ARES_EBADRESP` early for malformed packets + +## Why this approach? + +This keeps the parser aligned with its natural flow: + +parse header → parse question → validate → preallocate → parse records + +It avoids trusting unverified input and ensures malformed packets are +rejected early and consistently. + +## Test + +Added a regression test (`ParseMalformedRRCount`) that reproduces the +issue using a malformed packet with inconsistent RR count. + +Signed-off-by: @jmestwa-coder + +CVE: CVE-2026-69186 +Upstream-Status: Backport [https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4] +Signed-off-by: Peter Marko +--- + src/lib/ares_dns_parse.c | 55 ++++++++++++++++++++++------------------ + test/ares-test-parse.cc | 11 ++++++++ + 2 files changed, 42 insertions(+), 24 deletions(-) + +diff --git a/src/lib/ares_dns_parse.c b/src/lib/ares_dns_parse.c +index 2d2a7bb2..01f3f43c 100644 +--- a/src/lib/ares_dns_parse.c ++++ b/src/lib/ares_dns_parse.c +@@ -848,30 +848,6 @@ static ares_status_t ares_dns_parse_header(ares__buf_t *buf, unsigned int flags, + + (*dnsrec)->raw_rcode = rcode; + +- if (*ancount > 0) { +- status = +- ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_ANSWER, *ancount); +- if (status != ARES_SUCCESS) { +- goto fail; +- } +- } +- +- if (*nscount > 0) { +- status = +- ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_AUTHORITY, *nscount); +- if (status != ARES_SUCCESS) { +- goto fail; +- } +- } +- +- if (*arcount > 0) { +- status = +- ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_ADDITIONAL, *arcount); +- if (status != ARES_SUCCESS) { +- goto fail; +- } +- } +- + return ARES_SUCCESS; + + fail: +@@ -1134,6 +1110,8 @@ static ares_status_t ares_dns_parse_buf(ares__buf_t *buf, unsigned int flags, + ares_dns_record_t **dnsrec) + { + ares_status_t status; ++ size_t total_rr_count; ++ const size_t min_rr_wire_len = 11; + unsigned short qdcount; + unsigned short ancount; + unsigned short nscount; +@@ -1194,6 +1172,35 @@ static ares_status_t ares_dns_parse_buf(ares__buf_t *buf, unsigned int flags, + } + } + ++ total_rr_count = (size_t)ancount + (size_t)nscount + (size_t)arcount; ++ if (total_rr_count > ares__buf_len(buf) / min_rr_wire_len) { ++ status = ARES_EBADRESP; ++ goto fail; ++ } ++ ++ if (ancount > 0) { ++ status = ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_ANSWER, ancount); ++ if (status != ARES_SUCCESS) { ++ goto fail; /* LCOV_EXCL_LINE: OutOfMemory */ ++ } ++ } ++ ++ if (nscount > 0) { ++ status = ++ ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_AUTHORITY, nscount); ++ if (status != ARES_SUCCESS) { ++ goto fail; /* LCOV_EXCL_LINE: OutOfMemory */ ++ } ++ } ++ ++ if (arcount > 0) { ++ status = ++ ares_dns_record_rr_prealloc(*dnsrec, ARES_SECTION_ADDITIONAL, arcount); ++ if (status != ARES_SUCCESS) { ++ goto fail; /* LCOV_EXCL_LINE: OutOfMemory */ ++ } ++ } ++ + /* Parse Answers */ + for (i = 0; i < ancount; i++) { + status = ares_dns_parse_rr(buf, flags, ARES_SECTION_ANSWER, *dnsrec); +diff --git a/test/ares-test-parse.cc b/test/ares-test-parse.cc +index ff1fe14d..81fd7deb 100644 +--- a/test/ares-test-parse.cc ++++ b/test/ares-test-parse.cc +@@ -207,6 +207,17 @@ TEST_F(LibraryTest, ParseFullyCompressedName) { + ares_free_hostent(host); + } + ++TEST_F(LibraryTest, ParseMalformedRRCount) { ++ ares_dns_record_t *dnsrec = NULL; ++ const unsigned char data[] = { ++ 0x12, 0x34, 0x81, 0x80, 0x00, 0x01, 0x00, 0x01, ++ 0x00, 0x00, 0x00, 0x00, 0x01, 'a', 0x00, 0x00, ++ 0x01, 0x00, 0x01, ++ }; ++ ++ EXPECT_EQ(ARES_EBADRESP, ares_dns_parse(data, sizeof(data), 0, &dnsrec)); ++ EXPECT_EQ(nullptr, dnsrec); ++} + + } // namespace test + } // namespace ares diff --git a/meta-oe/recipes-support/c-ares/c-ares_1.27.0.bb b/meta-oe/recipes-support/c-ares/c-ares_1.27.0.bb index f6de281058..f409899026 100644 --- a/meta-oe/recipes-support/c-ares/c-ares_1.27.0.bb +++ b/meta-oe/recipes-support/c-ares/c-ares_1.27.0.bb @@ -6,7 +6,9 @@ LICENSE = "MIT" LIC_FILES_CHKSUM = "file://LICENSE.md;md5=fdbc58a6da11a9f68aa73c453818decc" SRC_URI = "https://github.com/c-ares/c-ares/releases/download/cares-1_27_0/${BPN}-${PV}.tar.gz \ - file://run-ptest" + file://run-ptest \ + file://CVE-2026-69186.patch \ +" SRC_URI[sha256sum] = "0a72be66959955c43e2af2fbd03418e82a2bd5464604ec9a62147e37aceb420b" PACKAGECONFIG ?= "${@bb.utils.contains('PTEST_ENABLED', '1', 'tests', '', d)}"