[wrynose][PATCH 6/7] libpcap: Fix CVE-2026-18313

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

NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18313
Upstream-commit: https://github.com/the-tcpdump-group/libpcap/commit/f9775af1a0ec76db60c7213241e6b48f1be10ac7
Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
---
 .../libpcap/libpcap/06-CVE-2026-18313.patch   | 104 ++++++++++++++++++
 .../libpcap/libpcap_1.10.6.bb                 |   1 +
 2 files changed, 105 insertions(+)
 create mode 100644 meta/recipes-connectivity/libpcap/libpcap/06-CVE-2026-18313.patch

diff --git a/meta/recipes-connectivity/libpcap/libpcap/06-CVE-2026-18313.patch b/meta/recipes-connectivity/libpcap/libpcap/06-CVE-2026-18313.patch
new file mode 100644
index 0000000000..7e6868898a
--- /dev/null
+++ b/meta/recipes-connectivity/libpcap/libpcap/06-CVE-2026-18313.patch
@@ -0,0 +1,104 @@
+From b039b8b66616852673c21ec5c7e0bad3190eae59 Mon Sep 17 00:00:00 2001
+From: Denis Ovsienko <denis@ovsienko.info>
+Date: Sat, 1 Aug 2026 18:24:48 +0100
+Subject: [PATCH] CVE-2026-18313: Fix a memory leak in rpcapd.
+
+This vulnerability was originally reported publicly, hence no credit is
+given.
+
+daemon_unpackapplyfilter() can allocate a temporary buffer for up to
+RPCAP_BPF_MAXINSNS (8192) BPF instructions (65536 bytes) per each
+received RPCAP_MSG_UPDATEFILTER_REQ or RPCAP_MSG_STARTCAP_REQ message.
+It never frees the memory, so repeated messages from a client will
+eventually leak enough memory on the server to cause problems.  This
+holds for all connections that pass the validation and some connections
+that do not.
+
+48 bytes in 1 blocks are definitely lost in loss record 2 of 2
+   at 0x4844818: malloc (vg_replace_malloc.c:446)
+   by 0x111AAB: daemon_unpackapplyfilter (daemon.c:2372)
+   by 0x113279: daemon_msg_startcap_req.constprop.0 (daemon.c:2139)
+   by 0x114808: daemon_serviceloop (daemon.c:901)
+   by 0x115BC7: accept_connection (rpcapd.c:1321)
+   by 0x115BC7: accept_connections (rpcapd.c:1118)
+   by 0x115BC7: main_startup (rpcapd.c:709)
+   by 0x1112BD: main (rpcapd.c:567)
+
+To fix this, after a successful malloc() return exactly once, after the
+free() call.
+
+(backported from commit 26a1c75702b105ac8788014f35f1b5c57fa6043b)
+
+(cherry picked from commit f9775af1a0ec76db60c7213241e6b48f1be10ac7)
+
+Upstream-Status: Backport [https://github.com/the-tcpdump-group/libpcap/commit/f9775af1a0ec76db60c7213241e6b48f1be10ac7]
+CVE: CVE-2026-18313
+
+Notes on backporting to 1.10.6:
+ - The upstream commit was made after the "bogus instructions" -> "invalid
+   instructions" message change (commit 836d0fd0), which is not backported.
+   The 1.10.6 wording ("The filter contains bogus instructions") is therefore
+   kept; only the memory-leak fix (goto free_and_return_status / free()) is
+   applied.
+
+Signed-off-by: Jaipaul Cheernam <jaipaul.cheernam@est.tech>
+---
+ CHANGES                  | 2 ++
+ rpcapd/daemon.c | 19 ++++++++-----------
+ 2 files changed, 10 insertions(+), 11 deletions(-)
+diff --git a/CHANGES b/CHANGES
+index ff9bac3..4f24f94 100644
+--- a/CHANGES
++++ b/CHANGES
+@@ -5,6 +5,7 @@
+     CVE-2026-31911: Fail opcodes safely in the BPF interpreter.
+     CVE-2026-6244: Avoid division by zero via pcap_offline_filter().
+     CVE-2026-6554: Limit "ja L" looping in pcap_offline_filter().
++    CVE-2026-18313: Fix a memory leak in rpcapd.
+ 
+ Tuesday, December 30, 2025 / The Tcpdump Group
+   Summary for 1.10.6 libpcap release
+diff --git a/rpcapd/daemon.c b/rpcapd/daemon.c
+index 87274665..b720cc45 100644
+--- a/rpcapd/daemon.c
++++ b/rpcapd/daemon.c
+@@ -2380,14 +2380,8 @@ daemon_unpackapplyfilter(PCAP_SOCKET sockctrl, SSL *ctrl_ssl, struct session *se
+ 	{
+ 		status = rpcapd_recv(sockctrl, ctrl_ssl, (char *) &insn,
+ 		    sizeof(struct rpcap_filterbpf_insn), plenp, errmsgbuf);
+-		if (status == -1)
+-		{
+-			return -1;
+-		}
+-		if (status == -2)
+-		{
+-			return -2;
+-		}
++		if (status == -1 || status == -2)
++			goto free_and_return_status;
+ 
+ 		bf_insn->code = ntohs(insn.code);
+ 		bf_insn->jf = insn.jf;
+@@ -2403,16 +2397,19 @@ daemon_unpackapplyfilter(PCAP_SOCKET sockctrl, SSL *ctrl_ssl, struct session *se
+ 	if (bpf_validate(bf_prog.bf_insns, bf_prog.bf_len) == 0)
+ 	{
+ 		snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "The filter contains bogus instructions");
+-		return -2;
++		status = -2;
++		goto free_and_return_status;
+ 	}
+ 
+ 	if (pcap_setfilter(session->fp, &bf_prog))
+ 	{
+ 		snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "RPCAP error: %s", pcap_geterr(session->fp));
+-		return -2;
++		status = -2;
+ 	}
+ 
+-	return 0;
++free_and_return_status:
++	free(bf_prog.bf_insns);
++	return status;
+ }
+ 
+ static int
diff --git a/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb b/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
index 6ca75117e1..859897acc5 100644
--- a/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
+++ b/meta/recipes-connectivity/libpcap/libpcap_1.10.6.bb
@@ -17,6 +17,7 @@ SRC_URI = "https://www.tcpdump.org/release/${BP}.tar.xz \
 	   file://03-CVE-2026-31911.patch \
 	   file://04-CVE-2026-6244.patch \
 	   file://05-CVE-2026-6554.patch \
+	   file://06-CVE-2026-18313.patch \
           "
 SRC_URI[sha256sum] = "ec97d1206bdd19cb6bdd043eaa9f0037aa732262ec68e070fd7c7b5f834d5dfc"