{"id":"CVE-2026-74702","summary":"vhost-scsi: reject feature changes after endpoint","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvhost-scsi: reject feature changes after endpoint\n\nvhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates\neach command's protection scatterlist array (prot_sgl) according to the\nacknowledged VIRTIO_SCSI_F_T10_PI bit.  The command pools are not rebuilt\nwhen VHOST_SET_FEATURES changes that bit later.\n\nAlthough virtio feature bits must not change after feature negotiation,\nvhost_scsi_set_features() currently accepts such a request after the\nendpoint is active and updates acked_features.  Enabling T10-PI after\nendpoint setup therefore leaves prot_sgl NULL while the I/O path follows\nthe new feature bit.\n\nFor a 129-page protection payload, vhost_scsi_mapal() passes the missing\nfirst chunk to sg_alloc_table_chained():\n\n  sg_alloc_table_chained(table, 129, first_chunk=NULL,\n                         nents_first_chunk=inline_sg_cnt)\n\nsg_pool_index() then hits:\n\n  BUG_ON(nents \u003e SG_CHUNK_SIZE);   /* 129 \u003e 128 */\n\nThe kernel reported the following call trace and register state:\n\n  Call Trace:\n   \u003cTASK\u003e\n   ? __sg_alloc_table+0x1d8/0x250\n   ? __pfx_vhost_run_work_list+0x10/0x10 [vhost]\n   sg_alloc_table_chained+0x59/0xf0\n   ? __pfx_sg_pool_alloc+0x10/0x10\n   ? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi]\n   vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi]\n   ? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi]\n   vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi]\n   vhost_run_work_list+0x8e/0xd0 [vhost]\n   vhost_task_fn+0xe1/0x210\n   ret_from_fork+0x348/0x540\n   \u003c/TASK\u003e\n\n  RIP: 0010:0x4\n  CR2 = 0x4\n  RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202\n  RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000\n  RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081\n\nVHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only\nexception.\n\nReject changes to any feature other than VHOST_F_LOG_ALL while the\nendpoint is active.  This preserves the existing runtime log toggle while\npreventing feature-dependent command resources and data-path state from\nbecoming inconsistent.  Userspace must clear the endpoint before changing\nany other negotiated feature and set the endpoint up again afterward.","modified":"2026-08-27T11:31:14.001098330Z","published":"2026-08-22T15:33:02.223Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74702.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/42bc45df5905e2b7dccb72adaf7730f66cfbe03f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a3eb77a612f9d158e4d27df43677a014e9cfa55"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a06e4611d45518896fbff4f45d9581578b107e91"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74702.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74702"},{"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":"bf2d650391be508dd8b5e188b65ed32300cf3489"},{"fixed":"a06e4611d45518896fbff4f45d9581578b107e91"},{"fixed":"9a3eb77a612f9d158e4d27df43677a014e9cfa55"},{"fixed":"42bc45df5905e2b7dccb72adaf7730f66cfbe03f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74702.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.15.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74702.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}