{"id":"CVE-2026-90125","state":"PUBLISHED","title":"smb: client: fix request buffer leak in smb2_new_read_req()","description":"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->tcon, 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->mr = smbd_register_mr(server->smbd_conn,\n\t\t\t\t\t     &rdata->subreq.io_iter,\n\t\t\t\t\t     true, need_invalidate);\n\t\tif (!rdata->mr)\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->mr = smbd_register_mr(...);\n\tif (!wdata->mr) {\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->retry, 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().","publishedAt":"2026-09-17T16:06:27.924Z","updatedAt":"2026-10-30T12:34:16.330Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"38daae149c2102d96833cc6acd79c8f98fcce208","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"58066940076b90c16e821fd6f9767cd979cbdb5e","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"12092ed28434bf41e08d41e3c5269eb6b337fc02","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"442c5f1358ced0d4e716778ac06f1e323a7e4f21","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"73f6bdb0380486ab37fe12cd74de20abfaf5d3ae","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"deb6468f4164640e4dc875f008aa449cf55987a5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]}],"references":["https://git.kernel.org/stable/c/38daae149c2102d96833cc6acd79c8f98fcce208","https://git.kernel.org/stable/c/58066940076b90c16e821fd6f9767cd979cbdb5e","https://git.kernel.org/stable/c/12092ed28434bf41e08d41e3c5269eb6b337fc02","https://git.kernel.org/stable/c/442c5f1358ced0d4e716778ac06f1e323a7e4f21","https://git.kernel.org/stable/c/73f6bdb0380486ab37fe12cd74de20abfaf5d3ae","https://git.kernel.org/stable/c/deb6468f4164640e4dc875f008aa449cf55987a5"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90125.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90125","state":"PUBLISHED","datePublished":"2026-09-17T16:06:27.924Z","dateUpdated":"2026-10-30T12:34:16.330Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.788Z"},"containers":{"cna":{"title":"smb: client: fix request buffer leak in smb2_new_read_req()","descriptions":[{"lang":"en","value":"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->tcon, 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->mr = smbd_register_mr(server->smbd_conn,\n\t\t\t\t\t     &rdata->subreq.io_iter,\n\t\t\t\t\t     true, need_invalidate);\n\t\tif (!rdata->mr)\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->mr = smbd_register_mr(...);\n\tif (!wdata->mr) {\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->retry, 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()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"38daae149c2102d96833cc6acd79c8f98fcce208","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"58066940076b90c16e821fd6f9767cd979cbdb5e","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"12092ed28434bf41e08d41e3c5269eb6b337fc02","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"442c5f1358ced0d4e716778ac06f1e323a7e4f21","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"73f6bdb0380486ab37fe12cd74de20abfaf5d3ae","versionType":"git"},{"version":"bd3dcc6a22a9186ed78da51ce09e889803552189","status":"affected","lessThan":"deb6468f4164640e4dc875f008aa449cf55987a5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/38daae149c2102d96833cc6acd79c8f98fcce208"},{"url":"https://git.kernel.org/stable/c/58066940076b90c16e821fd6f9767cd979cbdb5e"},{"url":"https://git.kernel.org/stable/c/12092ed28434bf41e08d41e3c5269eb6b337fc02"},{"url":"https://git.kernel.org/stable/c/442c5f1358ced0d4e716778ac06f1e323a7e4f21"},{"url":"https://git.kernel.org/stable/c/73f6bdb0380486ab37fe12cd74de20abfaf5d3ae"},{"url":"https://git.kernel.org/stable/c/deb6468f4164640e4dc875f008aa449cf55987a5"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:34:16.330Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}