{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89532","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.720Z","datePublished":"2026-09-11T19:44:11.495Z","dateUpdated":"2026-09-14T12:00:42.875Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:00:42.875Z"},"descriptions":[{"lang":"en","value":"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 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."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - svcrdma is the nfsd RPC-over-RDMA server transport and parses Write/Reply chunks from remote peers over iWARP or routable RoCEv2; a remote NFS/RDMA client triggers the bug with a crafted transport header on an established RDMA connection.\nAC:L - The attacker sets RPCRDMA_CMP_F_SND_W_INV_OK on connect and sends a Write or Reply chunk with segcount 0, which xdr_check_write_chunk accepts; Send-With-Invalidate is available on typical RDMA devices, so svc_rdma_get_inv_rkey hits the underflow deterministically.\nPR:N - svc_rdma_xdr_decode_req and svc_rdma_get_inv_rkey run in svc_rdma_recvfrom before svc_process/svc_authenticate; RDMA CM accept and RPC-over-RDMA header parsing require no NFS credentials or capabilities.\nUI:N - Exploitation requires only attacker-generated RDMA connect and RPC-over-RDMA messages to a listening NFS/RDMA service; no victim user action is needed.\nS:U - The out-of-bounds read and resulting general protection fault occur in the host kernel NFS/RDMA server and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - With ch_segcount 0, pcl_for_each_segment underflows the u32 bound to 0xFFFFFFFF and walks adjacent kernel heap at sizeof(struct svc_rdma_segment) stride, an unbounded out-of-bounds read rather than a few-byte leak.\nI:N - svc_rdma_get_inv_rkey only loads segment->rs_handle from the overrun pointer; the defect is a read-only walk with no out-of-bounds write, use-after-free, or control-flow hijack primitive.\nA:H - The unbounded walk continues until it hits unmapped memory and raises a general protection fault, oopsing or panicking the kernel, and the attacker can repeat it on each request."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma_pcl.h"],"versions":[{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"1e2e3481e39103a386b86be1c33eaef97cbdf16e","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"3a78b841879c2a3243f74edc514236fb2907167f","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"06d0390c37fa6714624af771bd72bbf1a7ed9bb1","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"9c5a03c3dc505c0295339b0a1b9e4fe36447e482","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"6d33a7e6bf6c6b293a266a617201285a1ad32c56","status":"affected","versionType":"git"},{"version":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2","lessThan":"b7713a784c59515d0aba558c8f5df6a0164dd3a9","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/sunrpc/svc_rdma_pcl.h"],"versions":[{"version":"5.11","status":"affected"},{"version":"0","lessThan":"5.11","status":"unaffected","versionType":"semver"},{"version":"5.15.221","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.109","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.50","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"7.3-rc1"}]}]}],"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"}],"title":"svcrdma: Fix pcl_for_each_segment for empty chunks","x_generator":{"engine":"bippy-1.2.0"}}}}