{"id":"CVE-2026-23286","summary":"atm: lec: fix null-ptr-deref in lec_arp_clear_vccs","details":"In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix null-ptr-deref in lec_arp_clear_vccs\n\nsyzkaller reported a null-ptr-deref in lec_arp_clear_vccs().\nThis issue can be easily reproduced using the syzkaller reproducer.\n\nIn the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by\nmultiple lec_arp_table entries (e.g., via entry-\u003evcc or entry-\u003erecv_vcc).\nWhen the underlying VCC is closed, lec_vcc_close() iterates over all\nARP entries and calls lec_arp_clear_vccs() for each matched entry.\n\nFor example, when lec_vcc_close() iterates through the hlists in\npriv-\u003elec_arp_empty_ones or other ARP tables:\n\n1. In the first iteration, for the first matched ARP entry sharing the VCC,\nlec_arp_clear_vccs() frees the associated vpriv (which is vcc-\u003euser_back)\nand sets vcc-\u003euser_back to NULL.\n2. In the second iteration, for the next matched ARP entry sharing the same\nVCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from\nvcc-\u003euser_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\nvia `vcc-\u003epop = vpriv-\u003eold_pop`, leading to a null-ptr-deref crash.\n\nFix this by adding a null check for vpriv before dereferencing\nit. If vpriv is already NULL, it means the VCC has been cleared\nby a previous call, so we can safely skip the cleanup and just\nclear the entry's vcc/recv_vcc pointers.\n\nThe entire cleanup block (including vcc_release_async()) is placed inside\nthe vpriv guard because a NULL vpriv indicates the VCC has already been\nfully released by a prior iteration — repeating the teardown would\nredundantly set flags and trigger callbacks on an already-closing socket.\n\nThe Fixes tag points to the initial commit because the entry-\u003evcc path has\nbeen vulnerable since the original code. The entry-\u003erecv_vcc path was later\nadded by commit 8d9f73c0ad2f (\"atm: fix a memory leak of vcc-\u003euser_back\")\nwith the same pattern, and both paths are fixed here.","modified":"2026-04-14T03:48:32.985472Z","published":"2026-03-25T10:26:45.531Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23286.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2d9f57ea29a1f1772373b98a509b44d49fda609e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5f1cfea7921f5c126a441d973690eeba52677b64"},{"type":"WEB","url":"https://git.kernel.org/stable/c/622062f24644b4536d3f437e0cf7a8c4bb421665"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7ea92ab075d809ec8a96669a5ecf00f752057875"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e9665986eb127290ceb535bd5d04d7a84265d94f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23286.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23286"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2"},{"fixed":"e9665986eb127290ceb535bd5d04d7a84265d94f"},{"fixed":"622062f24644b4536d3f437e0cf7a8c4bb421665"},{"fixed":"2d9f57ea29a1f1772373b98a509b44d49fda609e"},{"fixed":"7ea92ab075d809ec8a96669a5ecf00f752057875"},{"fixed":"5f1cfea7921f5c126a441d973690eeba52677b64"},{"fixed":"101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23286.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.12"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.77"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.17"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23286.json"}}],"schema_version":"1.7.5"}