{"id":"CVE-2021-47559","state":"PUBLISHED","title":"net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()\n\nCoverity reports a possible NULL dereferencing problem:\n\nin smc_vlan_by_tcpsk():\n6. returned_null: netdev_lower_get_next returns NULL (checked 29 out of 30 times).\n7. var_assigned: Assigning: ndev = NULL return value from netdev_lower_get_next.\n1623                ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);\nCID 1468509 (#1 of 1): Dereference null return value (NULL_RETURNS)\n8. dereference: Dereferencing a pointer that might be NULL ndev when calling is_vlan_dev.\n1624                if (is_vlan_dev(ndev)) {\n\nRemove the manual implementation and use netdev_walk_all_lower_dev() to\niterate over the lower devices. While on it remove an obsolete function\nparameter comment.","publishedAt":"2024-05-24T15:12:48.675Z","updatedAt":"2026-08-05T08:48:24.200Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"c94cbd262b6aa3b54d73a1ed1f9c0d19df57f4ff","versionType":"git"},{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"bb851d0fb02547d03cd40106b5f2391c4fed6ed1","versionType":"git"},{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"587acad41f1bc48e16f42bb2aca63bf323380be8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"5.10.83","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.6","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_core.c"]}],"references":["https://git.kernel.org/stable/c/c94cbd262b6aa3b54d73a1ed1f9c0d19df57f4ff","https://git.kernel.org/stable/c/bb851d0fb02547d03cd40106b5f2391c4fed6ed1","https://git.kernel.org/stable/c/587acad41f1bc48e16f42bb2aca63bf323380be8"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47559.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47559","state":"PUBLISHED","datePublished":"2024-05-24T15:12:48.675Z","dateUpdated":"2026-08-05T08:48:24.200Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-05-24T15:11:00.727Z"},"containers":{"cna":{"title":"net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()\n\nCoverity reports a possible NULL dereferencing problem:\n\nin smc_vlan_by_tcpsk():\n6. returned_null: netdev_lower_get_next returns NULL (checked 29 out of 30 times).\n7. var_assigned: Assigning: ndev = NULL return value from netdev_lower_get_next.\n1623                ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);\nCID 1468509 (#1 of 1): Dereference null return value (NULL_RETURNS)\n8. dereference: Dereferencing a pointer that might be NULL ndev when calling is_vlan_dev.\n1624                if (is_vlan_dev(ndev)) {\n\nRemove the manual implementation and use netdev_walk_all_lower_dev() to\niterate over the lower devices. While on it remove an obsolete function\nparameter comment."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"c94cbd262b6aa3b54d73a1ed1f9c0d19df57f4ff","versionType":"git"},{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"bb851d0fb02547d03cd40106b5f2391c4fed6ed1","versionType":"git"},{"version":"cb9d43f6775457cac75544bc4197f26ac2b6f294","status":"affected","lessThan":"587acad41f1bc48e16f42bb2aca63bf323380be8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"5.10.83","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.6","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c94cbd262b6aa3b54d73a1ed1f9c0d19df57f4ff"},{"url":"https://git.kernel.org/stable/c/bb851d0fb02547d03cd40106b5f2391c4fed6ed1"},{"url":"https://git.kernel.org/stable/c/587acad41f1bc48e16f42bb2aca63bf323380be8"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - smc_vlan_by_tcpsk() runs on the SMC server listen path (smc_listen_work → smc_listen_find_device) during the CLC handshake over TCP after a remote peer connects to an AF_SMC listener, matching other SMC listen-path remote scores.\nAC:L - A remote peer only needs to complete a TCP connect with the SMC option and send a CLC proposal; stacked netdev topologies (bond/VLAN) are the intended, common deployment this walker exists for, so the attacker can trigger the path at will.\nPR:N - The CLC handshake runs before any application authentication and SMC performs no peer credential checks, so an unauthenticated remote client needs no account or capability on the target.\nUI:N - smc_listen_work runs automatically on inbound SMC/TCP connections with no additional victim action required beyond an already-listening SMC service.\nS:U - A successful trigger only oopses the local host kernel within the same security authority and does not cross a VM, IOMMU, or other boundary.\nC:N - This is a pure NULL pointer dereference of the netdev_lower_get_next() return in is_vlan_dev(), with no out-of-bounds read, UAF, or other information-disclosure primitive.\nI:N - The fault is a straight NULL dereference crash with no write primitive, type confusion, or memory corruption that could alter kernel state or hijack control flow.\nA:H - Dereferencing the NULL net_device pointer in is_vlan_dev() causes a kernel oops/panic and can take down the system, which is High availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:48:24.200Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.10.83"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.15.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.16"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2021-47559","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-05-24T19:14:31.432418Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-06-04T17:14:40.808Z"}},{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/c94cbd262b6aa3b54d73a1ed1f9c0d19df57f4ff","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/bb851d0fb02547d03cd40106b5f2391c4fed6ed1","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/587acad41f1bc48e16f42bb2aca63bf323380be8","tags":["x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-04T05:39:59.699Z"}}]}}}