{"id":"CVE-2026-80789","summary":"nvmet-tcp: bound SGL data length before allocating command buffers","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: bound SGL data length before allocating command buffers\n\nnvmet_tcp_map_data() reads the host-controlled 32-bit sgl-\u003elength\nand, for the in-capsule offset descriptor (type 0x01), checks it\nagainst port-\u003einline_data_size before use. Any other SGL descriptor\ntype -- including the non-inline transport SGL data-block descriptor\n(type (NVME_TRANSPORT_SGL_DATA_DESC \u003c\u003c 4) | NVME_SGL_FMT_TRANSPORT_A,\nthe type a real host uses for out-of-capsule writes) skips that check\nentirely and falls straight through to:\n\n\tcmd-\u003ereq.sg = sgl_alloc(len, GFP_KERNEL, &cmd-\u003ereq.sg_cnt);\n\nwith len taken directly from the wire, unbounded up to 4 GiB.\n\nnvmet_req_init() only parses the command and never inspects\nsgl-\u003elength, and nvmet_check_transfer_len() -- the only other place\ntransfer_len is validated -- runs later, from req-\u003eexecute(), after\nthe allocation has already happened. For a write command the target\nresponds with an R2T and parks the command waiting for the host to\nsend the data; if the host (or an unauthenticated peer that simply\nnever follows up) never does, the sgl_alloc() buffer stays resident\nfor the life of the command. NVMe/TCP has no mandatory authentication\nin the default configuration, so any peer able to reach the target\nportal and complete a Fabrics connect can drive this with a single\ncrafted command, repeatable across queues and connections for\namplification. This is unbounded kernel memory allocation\ntriggered by a remote, effectively unauthenticated peer.\n\nValidate len against the same NVMET_TCP_MAXH2CDATA ceiling this file\nalready uses to bound per-PDU H2C data, for every SGL descriptor type,\nbefore doing any allocation. This closes the gap for the non-inline\ndescriptor while leaving the existing, tighter inline_data_size check\nin place for the in-capsule case.\n\nRuntime-verified on a v6.19 KASAN stand: with this bound in place, a\ncrafted write command carrying an oversized non-inline SGL length is\nrejected before sgl_alloc() runs, where the same request previously\ndrove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that\nstayed resident pending an R2T the host never satisfies.","modified":"2026-09-06T03:46:16.438157293Z","published":"2026-09-04T15:13:01.161Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80789.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80789.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80789"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"872d26a391da92ed8f0c0f5cb5fef428067b7f30"},{"fixed":"f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5"},{"fixed":"f63e89a0310264264923f84406dea05fe752de62"},{"fixed":"0952541b153e258b99d39cdb03ea6919fdeb41d0"},{"fixed":"25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22"},{"fixed":"d2acc96c528d589f5827cfb90e8e9229dd9d8cb4"},{"fixed":"6d27199ebe8cb223022150f74be13f154a964474"},{"fixed":"14dbe37681a6a7e346fc147bb363ec7cca3180a0"},{"fixed":"d895e66628f939edbb98608f6e033d3d39e6e546"},{"fixed":"4a3f00262a044e8e15064b1a6860968bf0500bf4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80789.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.10.269"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.220"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.187"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.156"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.106"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.47"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.11"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.2.0"},{"fixed":"7.2.1"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80789.json"}}],"schema_version":"1.9.0"}