[wrynose][PATCH 3/7] libpcap: Fix CVE-2026-31911

[Jaipaul Cheernam <jaipaul.cheernam@est.tech>]

NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31911
Upstream-commit: https://github.com/the-tcpdump-group/libpcap/commit/a715bcdde830299cba4171514385cb17ec19b6e9
Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
---
 .../libpcap/libpcap/03-CVE-2026-31911.patch   | 57 +++++++++++++++++++
 .../libpcap/libpcap_1.10.6.bb                 |  1 +
 2 files changed, 58 insertions(+)
 create mode 100644 meta/recipes-connectivity/libpcap/libpcap/03-CVE-2026-31911.patch

diff --git a/meta/recipes-connectivity/libpcap/libpcap/03-CVE-2026-31911.patch b/meta/recipes-connectivity/libpcap/libpcap/03-CVE-2026-31911.patch
new file mode 100644
index 0000000000..a0c53f9a09
--- /dev/null
+++ b/meta/recipes-connectivity/libpcap/libpcap/03-CVE-2026-31911.patch
@@ -0,0 +1,57 @@
+From 0067e8fd1f3caf866da3d95508831389f3b20e11 Mon Sep 17 00:00:00 2001
+From: Denis Ovsienko <denis@ovsienko.info>
+Date: Thu, 30 Jul 2026 13:34:08 +0100
+Subject: [PATCH] CVE-2026-31911: Fail opcodes safely in the BPF interpreter.
+
+This vulnerability has been discovered by FuzzAnything Organization.
+
+The current revision of pcapint_filter_with_aux_data() calls abort() if
+the current instruction opcode is invalid, and assumes this never to be
+the case.  This holds for programs that have been generated by libpcap.
+
+However, this does not necessarily hold for programs that come from an
+external source via pcap_offline_filter() or [deprecated] bpf_filter().
+Furthermore, this does not necessarily hold for programs that have been
+validated by libpcap because the current revision of the validator has
+gaps in the checks and accepts a number of invalid opcodes (another
+commit addresses that).
+
+Thus in pcapint_filter_with_aux_data(), when the instruction opcode is
+invalid, just reject the packet.
+
+(backported from commit 4ccb54bf4946d31a248ec93bdbeaabd97fb9d8f7)
+
+(cherry picked from commit a715bcdde830299cba4171514385cb17ec19b6e9)
+
+Upstream-Status: Backport [https://github.com/the-tcpdump-group/libpcap/commit/a715bcdde830299cba4171514385cb17ec19b6e9]
+CVE: CVE-2026-31911
+Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
+---
+ CHANGES                  | 1 +
+ bpf_filter.c | 2 +-
+ 2 files changed, 2 insertions(+), 1 deletion(-)
+diff --git a/CHANGES b/CHANGES
+index ab812dd..f0b5974 100644
+--- a/CHANGES
++++ b/CHANGES
+@@ -2,6 +2,7 @@
+   Backported security fixes:
+     CVE-2026-0799: Access M[] safely in the BPF interpreter.
+     CVE-2026-31912: Mind the program bounds in pcap_offline_filter().
++    CVE-2026-31911: Fail opcodes safely in the BPF interpreter.
+ 
+ Tuesday, December 30, 2025 / The Tcpdump Group
+   Summary for 1.10.6 libpcap release
+diff --git a/bpf_filter.c b/bpf_filter.c
+index 4f9adeea..f8b842d6 100644
+--- a/bpf_filter.c
++++ b/bpf_filter.c
+@@ -152,7 +152,7 @@ pcapint_filter_with_aux_data(const struct bpf_insn *pc, const u_int proglen,
+ 		switch (pc->code) {
+ 
+ 		default:
+-			abort();
++			return 0;
+ 		case BPF_RET|BPF_K:
+ 			return (u_int)pc->k;
+ 
diff --git a/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb b/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
index aa5265a54c..da218bd87b 100644
--- a/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
+++ b/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
@@ -14,6 +14,7 @@ SRC_URI = "https://www.tcpdump.org/release/${BP}.tar.xz \
 	   file://0001-Fix-error-messages-about-32-bit-integer-overflow.patch \
 	   file://01-CVE-2026-0799.patch \
 	   file://02-CVE-2026-31912.patch \
+	   file://03-CVE-2026-31911.patch \
           "
 SRC_URI[sha256sum] = "ec97d1206bdd19cb6bdd043eaa9f0037aa732262ec68e070fd7c7b5f834d5dfc"