From eae38d8010e461f8f0d4a9ec27080eb89bc2e6fe Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Thu, 12 Feb 2026 15:17:05 +0100 Subject: [PATCH] CVE-2026-0915: Stack memory disclosure in getnetbyaddr Resolves: RHEL-141850 --- glibc-RHEL-141850.patch | 70 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 glibc-RHEL-141850.patch diff --git a/glibc-RHEL-141850.patch b/glibc-RHEL-141850.patch new file mode 100644 index 0000000..1d3cf7f --- /dev/null +++ b/glibc-RHEL-141850.patch @@ -0,0 +1,70 @@ +commit e56ff82d5034ec66c6a78f517af6faa427f65b0b +Author: Carlos O'Donell +Date: Thu Jan 15 15:09:38 2026 -0500 + + resolv: Fix NSS DNS backend for getnetbyaddr (CVE-2026-0915) + + The default network value of zero for net was never tested for and + results in a DNS query constructed from uninitialized stack bytes. + The solution is to provide a default query for the case where net + is zero. + + Adding a test case for this was straight forward given the existence of + tst-resolv-network and if the test is added without the fix you observe + this failure: + + FAIL: resolv/tst-resolv-network + original exit status 1 + error: tst-resolv-network.c:174: invalid QNAME: \146\218\129\128 + error: 1 test failures + + With a random QNAME resulting from the use of uninitialized stack bytes. + + After the fix the test passes. + + Additionally verified using wireshark before and after to ensure + on-the-wire bytes for the DNS query were as expected. + + No regressions on x86_64. + + Reviewed-by: Florian Weimer + +diff --git a/resolv/nss_dns/dns-network.c b/resolv/nss_dns/dns-network.c +index 74b78959c230a8e3..1912fef6f2284c2d 100644 +--- a/resolv/nss_dns/dns-network.c ++++ b/resolv/nss_dns/dns-network.c +@@ -208,6 +208,10 @@ _nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result, + sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2], + net_bytes[1], net_bytes[0]); + break; ++ default: ++ /* Default network (net is originally zero). */ ++ strcpy (qbuf, "0.0.0.0.in-addr.arpa"); ++ break; + } + + net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024); +diff --git a/resolv/tst-resolv-network.c b/resolv/tst-resolv-network.c +index 156cb5692b6a9a28..febb447f60814498 100644 +--- a/resolv/tst-resolv-network.c ++++ b/resolv/tst-resolv-network.c +@@ -46,6 +46,9 @@ handle_code (const struct resolv_response_context *ctx, + { + switch (code) + { ++ case 0: ++ send_ptr (b, qname, qclass, qtype, "0.in-addr.arpa"); ++ break; + case 1: + send_ptr (b, qname, qclass, qtype, "1.in-addr.arpa"); + break; +@@ -265,6 +268,9 @@ do_test (void) + "error: TRY_AGAIN\n"); + + /* Lookup by address, success cases. */ ++ check_reverse (0, ++ "name: 0.in-addr.arpa\n" ++ "net: 0x00000000\n"); + check_reverse (1, + "name: 1.in-addr.arpa\n" + "net: 0x00000001\n");