{"id":"CVE-2026-89532","title":"svcrdma: Fix pcl_for_each_segment for empty chunks","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Fix pcl_for_each_segment for empty chunks\n\nWhen a parsed chunk list contains a chunk whose ch_segcount is zero,\npcl_for_each_segment computes its inclusive upp…","severity":"critical","cvss":9.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","cvssSource":"cna","cwe":["CWE-125"],"vendor":"Linux","product":"Linux","affected":["Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 1e2e3481e39103a386b86be1c33eaef97cbdf16e","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 3a78b841879c2a3243f74edc514236fb2907167f","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 06d0390c37fa6714624af771bd72bbf1a7ed9bb1","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 9c5a03c3dc505c0295339b0a1b9e4fe36447e482","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 6d33a7e6bf6c6b293a266a617201285a1ad32c56","Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < b7713a784c59515d0aba558c8f5df6a0164dd3a9","Linux 5.11"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T19:23:11.362883Z"},"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:48:23.895Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89532","references":[{"url":"https://git.kernel.org/stable/c/1e2e3481e39103a386b86be1c33eaef97cbdf16e"},{"url":"https://git.kernel.org/stable/c/3a78b841879c2a3243f74edc514236fb2907167f"},{"url":"https://git.kernel.org/stable/c/06d0390c37fa6714624af771bd72bbf1a7ed9bb1"},{"url":"https://git.kernel.org/stable/c/9c5a03c3dc505c0295339b0a1b9e4fe36447e482"},{"url":"https://git.kernel.org/stable/c/a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8"},{"url":"https://git.kernel.org/stable/c/6d33a7e6bf6c6b293a266a617201285a1ad32c56"},{"url":"https://git.kernel.org/stable/c/b7713a784c59515d0aba558c8f5df6a0164dd3a9"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89532.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89532"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532488"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89532"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89532"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89532.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00502,"epssPercentile":0.42785,"scores":{"cna":9.1,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.452Z","slug":"CVE-2026-89532","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Fix pcl_for_each_segment for empty chunks\n\nWhen a parsed chunk list contains a chunk whose ch_segcount is zero,\npcl_for_each_segment computes its inclusive upper bound as\n&chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the\nsubtraction wraps to 0xFFFFFFFF and the bound lands far past the\nch_segments flex array. The loop body then walks unrelated memory at\nsizeof(struct svc_rdma_segment) stride until it faults.\n\nA zero-segcount chunk is reachable from the wire:\nxdr_check_write_chunk() only rejects segcount values greater than\nrc_maxpages, and pcl_alloc_write() links a freshly allocated chunk\nonto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs,\nso a Write or Reply chunk advertising zero segments leaves\nch_segcount == 0 on the list. When the transport has negotiated\nSend-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four\nPCLs with pcl_for_each_segment and dereferences segment->rs_handle\non each iteration, turning the underflow into an out-of-bounds read\nand a general protection fault.\n\n    xdr_check_write_list / xdr_check_reply_chunk\n      pcl_alloc_write()\n        chunk = pcl_alloc_chunk(...)  /* ch_segcount = 0 */\n        list_add_tail(&chunk->ch_list, &pcl->cl_chunks)\n        /* fill loop iterates zero times for wire segcount 0 */\n\n    svc_rdma_get_inv_rkey()\n      pcl_for_each_chunk(rc_write_pcl)\n        pcl_for_each_segment(segment, chunk)\n          pos <= &ch_segments[0u - 1u]  /* 0xFFFFFFFF */\n          segment->rs_handle            /* OOB read -> GPF */\n\nFix by switching the macro to a half-open upper bound that uses\nch_segcount directly. For ch_segcount == 0 the loop start equals the\nloop end and the body is skipped; for ch_segcount > 0 the iteration\nrange is unchanged. All six existing call sites in\nnet/sunrpc/xprtrdma/svc_rdma_recvfrom.c and\nnet/sunrpc/xprtrdma/svc_rdma_rw.c remain correct under the new bound,\nso no caller changes are needed.\n\n## Affected\n\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 1e2e3481e39103a386b86be1c33eaef97cbdf16e`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 3a78b841879c2a3243f74edc514236fb2907167f`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 06d0390c37fa6714624af771bd72bbf1a7ed9bb1`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 9c5a03c3dc505c0295339b0a1b9e4fe36447e482`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < 6d33a7e6bf6c6b293a266a617201285a1ad32c56`\n- `Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 < b7713a784c59515d0aba558c8f5df6a0164dd3a9`\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 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89532.json)","depth":"midnight","depthScore":50,"depthScoreParts":{"impact":50.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223293,"id":"CVE-2026-89532","ts":1792180047806,"field":"cvss","old":"7","new":"9.1"},{"seq":223292,"id":"CVE-2026-89532","ts":1792180047806,"field":"severity","old":"high","new":"critical"},{"seq":203869,"id":"CVE-2026-89532","ts":1789490210426,"field":"cvss","old":"9.1","new":"7"},{"seq":203868,"id":"CVE-2026-89532","ts":1789490210426,"field":"severity","old":"critical","new":"high"},{"seq":197967,"id":"CVE-2026-89532","ts":1789384321186,"field":"cvss","old":"5.9","new":"9.1"},{"seq":197966,"id":"CVE-2026-89532","ts":1789384321186,"field":"severity","old":"medium","new":"critical"},{"seq":183502,"id":"CVE-2026-89532","ts":1789356675632,"field":"cvss","old":"9.1","new":"5.9"},{"seq":183501,"id":"CVE-2026-89532","ts":1789356675632,"field":"severity","old":"critical","new":"medium"},{"seq":153324,"id":"CVE-2026-89532","ts":1789285350048,"field":"cvss","old":null,"new":"9.1"},{"seq":153323,"id":"CVE-2026-89532","ts":1789285350048,"field":"severity","old":"none","new":"critical"},{"seq":147139,"id":"CVE-2026-89532","ts":1789270196375,"field":"cvss","old":null,"new":"5.9"},{"seq":147138,"id":"CVE-2026-89532","ts":1789270196375,"field":"severity","old":"none","new":"medium"},{"seq":108882,"id":"CVE-2026-89532","ts":1789183729391,"field":"cvss","old":null,"new":"5.9"},{"seq":108881,"id":"CVE-2026-89532","ts":1789183729391,"field":"severity","old":"none","new":"medium"}]}