{"id":"CVE-2026-93228","summary":"svcrdma: Reject Write/Reply chunks with segcount 0","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Reject Write/Reply chunks with segcount 0\n\nA peer can send a Write or Reply chunk whose segcount field is zero.\nxdr_check_write_chunk() only rejects segcount \u003e rc_maxpages, so zero\npasses the range check, and xdr_inline_decode(stream, 0) returns the\ncurrent (non-NULL) cursor without advancing. The function returns\ntrue and pcl_alloc_write() then links a struct svc_rdma_chunk with\nch_segcount == 0 onto rc_write_pcl or rc_reply_pcl.\n\nAn earlier patch in this series made pcl_for_each_segment() safe for\nch_segcount == 0, so this no longer drives the memory walk it used\nto. Rejecting the malformed frame at the decode boundary is still\nworthwhile as defense in depth: it keeps degenerate zero-segment\nchunks off the parsed chunk lists entirely, so any future consumer\nthat walks ch_segments directly cannot observe one, and it makes the\nzero-floor easy to backport to trees where the macro change is more\nintrusive. RFC 8166 has no meaning for a Write/Reply chunk that\ndescribes no remote buffer, so no legitimate client is affected.\n\nxdr_check_reply_chunk() funnels Reply chunks through\nxdr_check_write_chunk() and inherits the same rejection.\n\npcl_alloc_write() also links each chunk onto the parsed chunk list\nbefore filling its segment array. If a future change weakens the\nsegcount-0 rejection, an incomplete chunk is visible to consumers\nduring the fill loop. Reorder so that list_add_tail() follows the\nsegment fill loop, ensuring only fully-populated chunks appear on\nthe list.","modified":"2026-09-26T03:46:43.330102194Z","published":"2026-09-24T15:29:10.087Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93228.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/45dbdb2637b7fc5f1355b588780d2a7fb0516805"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9808eb7656666acc7291bae9ab6b987bd16e47e0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a798714b58041e88716db3bf8fb03ae13eecd54a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93228.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93228"},{"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":"78147ca8b4a9b6cf0e597ddd6bf17959e08376c2"},{"fixed":"fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f"},{"fixed":"a798714b58041e88716db3bf8fb03ae13eecd54a"},{"fixed":"45dbdb2637b7fc5f1355b588780d2a7fb0516805"},{"fixed":"9808eb7656666acc7291bae9ab6b987bd16e47e0"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93228.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93228.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"}]}