{"id":"CVE-2026-90125","summary":"smb: client: fix request buffer leak in smb2_new_read_req()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix request buffer leak in smb2_new_read_req()\n\nsmb2_new_read_req() allocates the request buffer with\nsmb2_plain_req_init() but only publishes it to the caller with\n*buf = req at the very end of the function. Two error returns sit in\nbetween:\n\n\trc = smb2_plain_req_init(SMB2_READ, io_parms-\u003etcon, server,\n\t\t\t\t (void **) &req, total_len);\n\tif (rc)\n\t\treturn rc;\n\n\tif (server == NULL)\n\t\treturn -ECONNABORTED;\n\t[...]\n\t\trdata-\u003emr = smbd_register_mr(server-\u003esmbd_conn,\n\t\t\t\t\t     &rdata-\u003esubreq.io_iter,\n\t\t\t\t\t     true, need_invalidate);\n\t\tif (!rdata-\u003emr)\n\t\t\treturn -EAGAIN;\n\nOn either of them the buffer is neither released nor handed back, so\nit is leaked. The caller cannot clean up after it: smb2_async_readv()\ndoes 'goto out' on a non-zero return, which skips the\ncifs_small_buf_release(buf) at async_readv_out, and buf has not been\nassigned at that point in any case.\n\nThe write path has never had this problem. smb2_async_writev()\nregisters the memory region inline and jumps to its release label\ninstead of returning:\n\n\twdata-\u003emr = smbd_register_mr(...);\n\tif (!wdata-\u003emr) {\n\t\trc = -EAGAIN;\n\t\tgoto async_writev_out;\n\t}\n\nCommit b7972092199f (\"cifs: smbd: Retry on memory registration\nfailure\") changed both sides from -ENOBUFS to -EAGAIN in a single\npatch, which puts the two shapes next to each other.\n\nOnly the -EAGAIN return is reachable in practice, because\nsmb2_plain_req_init() calls smb2_reconnect() first and that already\nfails with -EIO when server is NULL, before anything is allocated.\nBoth returns are given the same treatment here rather than leaving\none of them correct only by accident.\n\nBecause -EAGAIN is a replayable error, the failure also reaches the\nretry block at the end of smb2_async_readv(), which marks the\nsubrequest NETFS_SREQ_NEED_RETRY, so a failing registration can be\nretried rather than ending the I/O, and every attempt that reaches it\nleaks another buffer. smb2_should_replay() short-circuits on\ntcon-\u003eretry, so on a hard mount the attempt count is not bounded by\nthe retrans setting.\n\nOnly the asynchronous read path is affected. The synchronous\nSMB2_read() caller passes rdata == NULL and the memory registration\nblock is guarded on rdata.\n\nThe memory registration failure path was pointed out by the Sashiko\nAI reviewer while it was reviewing an unrelated patch to\nsmb2_async_readv().","modified":"2026-09-19T03:47:24.959276573Z","published":"2026-09-17T16:06:27.924Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90125.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/12092ed28434bf41e08d41e3c5269eb6b337fc02"},{"type":"WEB","url":"https://git.kernel.org/stable/c/442c5f1358ced0d4e716778ac06f1e323a7e4f21"},{"type":"WEB","url":"https://git.kernel.org/stable/c/58066940076b90c16e821fd6f9767cd979cbdb5e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/73f6bdb0380486ab37fe12cd74de20abfaf5d3ae"},{"type":"WEB","url":"https://git.kernel.org/stable/c/deb6468f4164640e4dc875f008aa449cf55987a5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90125.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90125"},{"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":"bd3dcc6a22a9186ed78da51ce09e889803552189"},{"fixed":"58066940076b90c16e821fd6f9767cd979cbdb5e"},{"fixed":"12092ed28434bf41e08d41e3c5269eb6b337fc02"},{"fixed":"442c5f1358ced0d4e716778ac06f1e323a7e4f21"},{"fixed":"73f6bdb0380486ab37fe12cd74de20abfaf5d3ae"},{"fixed":"deb6468f4164640e4dc875f008aa449cf55987a5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90125.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.16.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90125.json"}}],"schema_version":"1.9.0"}