nvmet-tcp: bound SGL data length before allocating command buffers

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80789
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-04 16:18:05 UTC
Updated2026-09-04 16:18:05 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: bound SGL data length before allocating command buffers nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length and, for the in-capsule offset descriptor (type 0x01), checks it against port->inline_data_size before use. Any other SGL descriptor type -- including the non-inline transport SGL data-block descriptor (type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A, the type a real host uses for out-of-capsule writes) skips that check entirely and falls straight through to: cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt); with len taken directly from the wire, unbounded up to 4 GiB. nvmet_req_init() only parses the command and never inspects sgl->length, and nvmet_check_transfer_len() -- the only other place transfer_len is validated -- runs later, from req->execute(), after the allocation has already happened. For a write command the target responds with an R2T and parks the command waiting for the host to send the data; if the host (or an unauthenticated peer that simply never follows up) never does, the sgl_alloc() buffer stays resident for the life of the command. NVMe/TCP has no mandatory authentication in the default configuration, so any peer able to reach the target portal and complete a Fabrics connect can drive this with a single crafted command, repeatable across queues and connections for amplification. This is unbounded kernel memory allocation triggered by a remote, effectively unauthenticated peer. Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file already uses to bound per-PDU H2C data, for every SGL descriptor type, before doing any allocation. This closes the gap for the non-inline descriptor while leaving the existing, tighter inline_data_size check in place for the in-capsule case. Runtime-verified on a v6.19 KASAN stand: with this bound in place, a crafted write command carrying an oversized non-inline SGL length is rejected before sgl_alloc() runs, where the same request previously drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that stayed resident pending an R2T the host never satisfies.

Risk And Classification

EPSS: 0.002340000 probability, percentile 0.142170000 (date 2026-09-07)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 f63e89a0310264264923f84406dea05fe752de62 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 0952541b153e258b99d39cdb03ea6919fdeb41d0 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 d2acc96c528d589f5827cfb90e8e9229dd9d8cb4 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 6d27199ebe8cb223022150f74be13f154a964474 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 14dbe37681a6a7e346fc147bb363ec7cca3180a0 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 d895e66628f939edbb98608f6e033d3d39e6e546 git Not specified
CNA Linux Linux affected 872d26a391da92ed8f0c0f5cb5fef428067b7f30 4a3f00262a044e8e15064b1a6860968bf0500bf4 git Not specified
CNA Linux Linux affected 5.0 Not specified
CNA Linux Linux unaffected 5.0 semver Not specified
CNA Linux Linux unaffected 5.10.269 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.220 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.187 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.156 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.106 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.47 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.11 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2.1 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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