{"id":"CVE-2026-89533","title":"svcrdma: Fix offset arithmetic in read_chunk_range","summary":"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 spann…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-191"],"vendor":"Linux","product":"Linux","affected":["Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 10873311f91db9454e2fadbf9866bc819e0646d9","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < cba8543c18cf42fd80fd63effb6df6ff4f7e73ce","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 6ee4dc7476b3abc92ec1d444533a559f33f59561","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < a46b35f213c2426f5d6a0458a8f7e873fc59cdfd","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 4493c96bbd0068fadf69cbae8d13426202e34cdc","Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 4a44c140cc2f3643a39e258bb0c0ab9d0f494f5e","Linux 5.11"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:23:13.656876Z"},"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:48:24.875Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89533","references":[{"url":"https://git.kernel.org/stable/c/10873311f91db9454e2fadbf9866bc819e0646d9"},{"url":"https://git.kernel.org/stable/c/addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7"},{"url":"https://git.kernel.org/stable/c/cba8543c18cf42fd80fd63effb6df6ff4f7e73ce"},{"url":"https://git.kernel.org/stable/c/6ee4dc7476b3abc92ec1d444533a559f33f59561"},{"url":"https://git.kernel.org/stable/c/a46b35f213c2426f5d6a0458a8f7e873fc59cdfd"},{"url":"https://git.kernel.org/stable/c/4493c96bbd0068fadf69cbae8d13426202e34cdc"},{"url":"https://git.kernel.org/stable/c/4a44c140cc2f3643a39e258bb0c0ab9d0f494f5e"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89533.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89533"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532058"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89533"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89533"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89533.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00502,"epssPercentile":0.42784,"scores":{"cna":9.8,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.452Z","slug":"CVE-2026-89533","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 10873311f91db9454e2fadbf9866bc819e0646d9`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < cba8543c18cf42fd80fd63effb6df6ff4f7e73ce`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 6ee4dc7476b3abc92ec1d444533a559f33f59561`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < a46b35f213c2426f5d6a0458a8f7e873fc59cdfd`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 4493c96bbd0068fadf69cbae8d13426202e34cdc`\n- `Linux >= d7cc73972661be4a02a1b09f1d9b3283c6c05154 < 4a44c140cc2f3643a39e258bb0c0ab9d0f494f5e`\n- `Linux 5.11`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89533.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223297,"id":"CVE-2026-89533","ts":1792180049074,"field":"cvss","old":"7","new":"9.8"},{"seq":223296,"id":"CVE-2026-89533","ts":1792180049074,"field":"severity","old":"high","new":"critical"},{"seq":204181,"id":"CVE-2026-89533","ts":1789490237185,"field":"cvss","old":"9.8","new":"7"},{"seq":204180,"id":"CVE-2026-89533","ts":1789490237185,"field":"severity","old":"critical","new":"high"},{"seq":197979,"id":"CVE-2026-89533","ts":1789384321233,"field":"cvss","old":"5.9","new":"9.8"},{"seq":197978,"id":"CVE-2026-89533","ts":1789384321233,"field":"severity","old":"medium","new":"critical"},{"seq":183764,"id":"CVE-2026-89533","ts":1789356677288,"field":"cvss","old":"9.8","new":"5.9"},{"seq":183763,"id":"CVE-2026-89533","ts":1789356677288,"field":"severity","old":"critical","new":"medium"},{"seq":153326,"id":"CVE-2026-89533","ts":1789285350057,"field":"cvss","old":null,"new":"9.8"},{"seq":153325,"id":"CVE-2026-89533","ts":1789285350057,"field":"severity","old":"none","new":"critical"},{"seq":109596,"id":"CVE-2026-89533","ts":1789183732557,"field":"cvss","old":null,"new":"5.9"},{"seq":109595,"id":"CVE-2026-89533","ts":1789183732557,"field":"severity","old":"none","new":"medium"}]}