CVE-2026-89533: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9cp7-7xj6-hh85",
  "modified" : "2026-09-14T15:32:28Z",
  "published" : "2026-09-11T21:31:30Z",
  "aliases" : [ "CVE-2026-89533" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Fix offset arithmetic in read_chunk_range\n\nsvc_rdma_read_chunk_range() walks a Read chunk's segment list to\nbuild a sub-range starting at byte offset and spanning length bytes\nfor a Position-Zero or Call chunk. Two arithmetic defects in the\nper-segment loop produce wrong DMA lengths and a u32 underflow:\n\n    pcl_for_each_segment(segment, chunk) {\n            if (offset > segment->rs_length) {\n                    offset -= segment->rs_length;\n                    continue;\n            }\n\n            dummy.rs_handle = segment->rs_handle;\n            dummy.rs_length = min_t(u32, length,\n                                    segment->rs_length) - offset;\n            dummy.rs_offset = segment->rs_offset + offset;\n\nFirst, the skip predicate uses '>' instead of '>='. When offset\nequals the segment's full rs_length, the segment is fully consumed\nand should be skipped, but the loop falls through into the body.\nThe resulting dummy.rs_length is min_t(u32, length, rs_length) -\nrs_length, which underflows to a near-UINT_MAX u32 when length is\nsmaller than rs_length, or is zero otherwise.\n\nSecond, the length formula subtracts offset from the min_t() result\nrather than from segment->rs_length before the cap. For offset > 0\nthe segment's residual is rs_length - offset, not rs_length, so the\ncap must be applied to the residual. With the current bracketing,\nwhenever length is smaller than rs_length - offset the per-segment\nlength becomes length - offset instead of length, silently dropping\noffset bytes from the rebuilt chunk. Combined with the boundary\ncase above it also enables the u32 underflow path, which propagates\na huge nr_bvec into svc_rdma_build_read_segment() and a multi-MiB\nkmalloc_array_node() in svc_rdma_get_rw_ctxt().\n\nAdditionally, svc_rdma_read_call_chunk() can invoke this function\nwith length == 0 when the last Read chunk ends exactly at the end\nof the Call chunk. With the corrected >= predicate, every segment\nis skipped and the function returns the initial -EINVAL, rejecting\na valid request. Return success immediately when length is zero.\nAlso break out of the loop once length is fully consumed to avoid\npassing zero-length segments to svc_rdma_build_read_segment().\n\nFix by using '>=' so a fully-consumed segment is skipped, by\nmoving '- offset' inside min_t() so the cap is applied to the\nsegment's residual length, by returning success for zero-length\nrequests, and by stopping iteration when the requested range has\nbeen consumed.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-89533"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/10873311f91db9454e2fadbf9866bc819e0646d9"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/4493c96bbd0068fadf69cbae8d13426202e34cdc"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/4a44c140cc2f3643a39e258bb0c0ab9d0f494f5e"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/6ee4dc7476b3abc92ec1d444533a559f33f59561"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/a46b35f213c2426f5d6a0458a8f7e873fc59cdfd"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/cba8543c18cf42fd80fd63effb6df6ff4f7e73ce"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-11T20:19:36Z"
  }
}