NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18238 Upstream-commit: https://github.com/the-tcpdump-group/libpcap/commit/b9590d482986d64673712460aae1d48d11fa0473 Signed-off-by: Jaipaul Cheernam <[email protected]> --- .../libpcap/libpcap/07-CVE-2026-18238.patch | 219 ++++++++++++++++++ .../libpcap/libpcap_1.10.4.bb | 1 + 2 files changed, 220 insertions(+) create mode 100644 meta/recipes-connectivity/libpcap/libpcap/07-CVE-2026-18238.patch
diff --git a/meta/recipes-connectivity/libpcap/libpcap/07-CVE-2026-18238.patch b/meta/recipes-connectivity/libpcap/libpcap/07-CVE-2026-18238.patch new file mode 100644 index 0000000000..c981fa8ff1 --- /dev/null +++ b/meta/recipes-connectivity/libpcap/libpcap/07-CVE-2026-18238.patch @@ -0,0 +1,219 @@ +From b9590d482986d64673712460aae1d48d11fa0473 Mon Sep 17 00:00:00 2001 +From: Denis Ovsienko <[email protected]> +Date: Sat, 8 Aug 2026 00:31:10 +0100 +Subject: [PATCH] CVE-2026-18238: Fix RPCAP_MSG_PACKET validation. + +This vulnerability was originally reported publicly, hence no credit is +given. + +When pcap_read_nocb_remote() validates a received message, it does not +verify that there is a complete RPCAP_MSG_PACKET header in the rpcap +general payload, also it uses an incorrect value to validate the length +declared in the RPCAP_MSG_PACKET header. The latter can lead the +protocol client to over-read the message buffer by 20 bytes, which in at +least one scenario can cause a SIGSEGV. + +Fix this problem, as well as a potential integer overflow in the UDP +code path on 32-bit architectures. To make message encoding and +validation easier to follow, re-jig a few variables and update comments. + +(backported from commit 2d67e814e8d3791a8b508c359f94688c5669cce9) + +(cherry picked from commit b9590d482986d64673712460aae1d48d11fa0473) + +Upstream-Status: Backport [https://github.com/the-tcpdump-group/libpcap/commit/b9590d482986d64673712460aae1d48d11fa0473] +CVE: CVE-2026-18238 +Signed-off-by: Jaipaul Cheernam <[email protected]> +--- +diff --git a/pcap-rpcap.c b/pcap-rpcap.c +index 22fc7363..30fbd6d6 100644 +--- a/pcap-rpcap.c ++++ b/pcap-rpcap.c +@@ -388,10 +388,9 @@ rpcap_deseraddr(struct rpcap_sockaddr *sockaddrin, struct sockaddr_storage **soc + static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_char **pkt_data) + { + struct pcap_rpcap *pr = p->priv; /* structure used when doing a remote live capture */ +- struct rpcap_header *header; /* general header according to the RPCAP format */ +- struct rpcap_pkthdr *net_pkt_header; /* header of the packet, from the message */ ++ struct rpcap_header *gen_header; /* rpcap general header */ ++ struct rpcap_pkthdr *net_pkt_header; /* RPCAP_MSG_PACKET header */ + u_char *net_pkt_data; /* packet data from the message */ +- uint32 plen; + int retval = 0; /* generic return value */ + int msglen; + +@@ -448,13 +447,35 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + return 0; + + /* +- * We have to define 'header' as a pointer to a larger buffer, +- * because in case of UDP we have to read all the message within a single call ++ * pcap_startcapture_remote() has pointed p->buffer to a buffer large ++ * enough to contain all of the following data at once: ++ * ++ * - a fixed-size rpcap general header ++ * - a fixed-size RPCAP_MSG_PACKET header ++ * - p->snapshot worth of bytes of a captured packet ++ * ++ * This is sufficient for all code paths below. + */ +- header = (struct rpcap_header *) p->buffer; ++ gen_header = (struct rpcap_header *)p->buffer; + net_pkt_header = (struct rpcap_pkthdr *) ((char *)p->buffer + sizeof(struct rpcap_header)); + net_pkt_data = (u_char *)p->buffer + sizeof(struct rpcap_header) + sizeof(struct rpcap_pkthdr); + ++ /* ++ * Step 1: to receive a message that does not immediately look ++ * malformed, consider it as a fixed-size rpcap general header followed ++ * by a variable-size rpcap general payload and require: ++ * ++ * - a complete rpcap general header to land in the buffer, and ++ * - the header to declare an rpcap general payload length that fits ++ * in the buffer after the header, and ++ * - the complete declared payload to land in the buffer after the ++ * header. ++ * ++ * Since this step loosely corresponds to rpcap_process_msg_header(), ++ * which among other things converts rpcap_header.plen to host byte ++ * order, mimic that as well to produce a valid argument for ++ * rpcap_check_msg_ver() later on. ++ */ + if (pr->rmt_flags & PCAP_OPENFLAG_DATATX_UDP) + { + /* Read the entire message from the network */ +@@ -470,6 +491,8 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + /* Interrupted receive. */ + return 0; + } ++ ++ // Require a complete rpcap general header to be present. + if ((size_t)msglen < sizeof(struct rpcap_header)) + { + /* +@@ -479,8 +502,18 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + "UDP packet message is shorter than an rpcap header"); + return -1; + } +- plen = ntohl(header->plen); +- if ((size_t)msglen < sizeof(struct rpcap_header) + plen) ++ gen_header->plen = ntohl(gen_header->plen); ++ ++ /* ++ * Validate the rpcap general payload length declared in the ++ * rpcap general header. Use subtraction to avoid an integer ++ * overflow: ++ * ++ * 0 <= gen_header->plen <= UINT32_MAX ++ * sizeof(struct rpcap_header) <= msglen <= p->bufsize ++ * p->bufsize is significantly less than UINT32_MAX ++ */ ++ if (gen_header->plen > (size_t)msglen - sizeof(struct rpcap_header)) + { + /* + * Message is shorter than the header claims it +@@ -495,6 +528,7 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + { + int status; + ++ // Receive a complete rpcap general header from the network. + if ((size_t)p->cc < sizeof(struct rpcap_header)) + { + /* +@@ -514,27 +548,35 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + return 0; + } + } ++ gen_header->plen = ntohl(gen_header->plen); + + /* +- * We have the header, so we know how long the +- * message payload is. The size we should get +- * is the size of the packet header plus the +- * size of the payload. ++ * Validate the rpcap general payload length declared in the ++ * rpcap general header. Use subtraction to avoid an integer ++ * overflow: ++ * ++ * 0 <= gen_header->plen <= UINT32_MAX ++ * sizeof(struct rpcap_header) < p->bufsize ++ * p->bufsize is significantly less than UINT32_MAX + */ +- plen = ntohl(header->plen); +- if (plen > p->bufsize - sizeof(struct rpcap_header)) ++ if (gen_header->plen > p->bufsize - sizeof(struct rpcap_header)) + { + /* + * This is bigger than the largest +- * record we'd expect. (We do it by +- * subtracting in order to avoid an +- * overflow.) ++ * record we'd expect. + */ + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, + "Server sent us a message larger than the largest expected packet message"); + return -1; + } +- status = rpcap_read_packet_msg(pr, p, sizeof(struct rpcap_header) + plen); ++ ++ /* ++ * Receive the declared rpcap general payload from the network. ++ * ++ * p->cc == sizeof(struct rpcap_header) ++ * p->bp == p->buffer + sizeof(struct rpcap_header) ++ */ ++ status = rpcap_read_packet_msg(pr, p, sizeof(struct rpcap_header) + gen_header->plen); + if (status == -1) + { + /* Network error. */ +@@ -557,27 +599,36 @@ static int pcap_read_nocb_remote(pcap_t *p, struct pcap_pkthdr *pkt_header, u_ch + + /* + * We have the entire message. +- */ +- header->plen = plen; +- +- /* +- * Did the server specify the version we negotiated? ++ * Step 2: to validate the received message further, require: ++ * ++ * - the rpcap general header to have the correct version and type, and ++ * - the rpcap general payload to be large enough to contain at least a ++ * complete RPCAP_MSG_PACKET header, and ++ * - the RPCAP_MSG_PACKET header to declare an RPCAP_MSG_PACKET payload ++ * (i.e. the captured packet) length that fits in the rpcap general ++ * payload (not the entire buffer) after the RPCAP_MSG_PACKET header. + */ + if (rpcap_check_msg_ver(pr->rmt_sockdata, pr->data_ssl, pr->protocol_version, +- header, p->errbuf) == -1) +- { ++ gen_header, p->errbuf) == -1) ++ return 0; /* Return 'no packets received' */ ++ if (gen_header->type != RPCAP_MSG_PACKET) + return 0; /* Return 'no packets received' */ ++ if (gen_header->plen < sizeof(struct rpcap_pkthdr)) ++ { ++ snprintf(p->errbuf, PCAP_ERRBUF_SIZE, ++ "Received an incomplete RPCAP_MSG_PACKET header."); ++ return -1; + } +- + /* +- * Is this a RPCAP_MSG_PACKET message? ++ * Validate the RPCAP_MSG_PACKET payload length declared in the ++ * RPCAP_MSG_PACKET header. Use subtraction to avoid an integer ++ * overflow: ++ * ++ * 0 <= ntohl(net_pkt_header->caplen) <= UINT32_MAX ++ * sizeof(struct rpcap_pkthdr) <= gen_header->plen ++ * gen_header->plen is significantly less than UINT32_MAX + */ +- if (header->type != RPCAP_MSG_PACKET) +- { +- return 0; /* Return 'no packets received' */ +- } +- +- if (ntohl(net_pkt_header->caplen) > plen) ++ if (ntohl(net_pkt_header->caplen) > gen_header->plen - sizeof(struct rpcap_pkthdr)) + { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, + "Packet's captured data goes past the end of the received packet message."); diff --git a/meta/recipes-connectivity/libpcap/libpcap_1.10.4.bb b/meta/recipes-connectivity/libpcap/libpcap_1.10.4.bb index 5f1506f8fc..3892454a40 100644 --- a/meta/recipes-connectivity/libpcap/libpcap_1.10.4.bb +++ b/meta/recipes-connectivity/libpcap/libpcap_1.10.4.bb @@ -23,6 +23,7 @@ SRC_URI = "https://www.tcpdump.org/release/${BP}.tar.gz \ file://04-CVE-2026-6244.patch \ file://05-CVE-2026-6554.patch \ file://06-CVE-2026-18313.patch \ + file://07-CVE-2026-18238.patch \ " SRC_URI[sha256sum] = "ed19a0383fad72e3ad435fd239d7cd80d64916b87269550159d20e47160ebe5f"
-=-=-=-=-=-=-=-=-=-=-=- Links: You receive all messages sent to this group. View/Reply Online (#245898): https://lists.openembedded.org/g/openembedded-core/message/245898 Mute This Topic: https://lists.openembedded.org/mt/121267553/21656 Group Owner: [email protected] Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
