{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72473", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.934Z", "datePublished": "2026-08-15T05:57:14.412Z", "dateUpdated": "2026-08-17T05:44:39.513Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:44:39.513Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxprtrdma: Decouple req recycling from RPC completion\n\nrl_kref formerly served two distinct lifetimes through a single\nrefcount: it gated when a Reply could wake its RPC task, and it\ngated when an rpcrdma_req could return to its free pool. The\nmarshal path took the Send-side reference only when SGEs needed\nDMA-unmap (sc_unmap_count > 0), which made a Send carrying only\npre-registered buffers an exception: the Reply handler dropped\nrl_kref from 1 to 0 and freed the req while the HCA might still\nbe DMA-reading from its send buffer.\n\nGive rl_kref a narrower job. The RPC layer takes one reference\nwhen slot allocation hands a req out. rpcrdma_prepare_send_sges()\ntakes a Send-side reference unconditionally after WR preparation\nsucceeds. xprt_rdma_free_slot() and xprt_rdma_bc_free_rqst() drop\nthe RPC-layer reference; rpcrdma_sendctx_unmap() drops the\nSend-side reference. The req returns to its free pool only after\nboth owners have signed off.\n\nThe existing kref_init(&req->rl_kref) call in\nrpcrdma_prepare_send_sges() is removed. Initialization moves to\nthe slot-allocation paths (xprt_rdma_alloc_slot and\nrpcrdma_bc_rqst_get), and the release callback re-arms rl_kref\nbefore the req returns to a free pool. A re-init in the marshal\npath would discard the RPC-layer reference that already exists\non entry.\n\nThree invariants follow:\n\n - Any rpcrdma_req held by an rpc_rqst has rl_kref >= 1.\n xprt_rdma_alloc_slot(), rpcrdma_bc_rqst_get(), and the\n backlog-wake branch in xprt_rdma_alloc_slot() each kref_init\n rl_kref before publishing the req. Without this invariant,\n an RPC task that aborts between slot allocation and marshal\n (gss_refresh failure or signal during call_connect, for\n example) would drive xprt_release() ->\n xprt_rdma_free_slot() -> kref_put against a refcount of\n zero, saturating refcount_t and stranding the slot.\n\n - The Send-side reference is taken only after WR prep\n succeeds. A mapping failure in rpcrdma_prepare_send_sges()\n runs rpcrdma_sendctx_cancel(), which DMA-unmaps the sendctx\n and clears sc_req without touching rl_kref. The sendctx\n ring walks in rpcrdma_sendctx_put_locked() and\n rpcrdma_sendctxs_destroy() skip entries with sc_req == NULL,\n so a burst of -EIO marshal failures cannot hold reqs off\n rb_send_bufs.\n\n - The release callback re-arms rl_kref so the next consumer\n enters with the invariant satisfied.\n\nReplies now complete the RPC directly. rpcrdma_reply_handler()\ncalls rpcrdma_complete_rqst() in place of kref_put on the\nnon-LocalInv branch. The LocalInv branch already completes the\nRPC from frwr_unmap_async() and is unaffected.\n\nBecause Send-side references can now outlive RPC completion,\nconnection teardown drains sendctx entries whose unsignaled\nSends never had a later signaled completion to walk the ring.\nrpcrdma_sendctxs_destroy() walks the active range and runs\nrpcrdma_sendctx_unmap() on each entry with a non-NULL sc_req\nbefore the request buffers are reset, and is moved ahead of\nrpcrdma_reqs_reset() in rpcrdma_xprt_disconnect() so the reqs\nare still in their pre-reset state when the Send-side refs are\nreleased.\n\nThe drain creates a teardown-ordering hazard on the backchannel\npath. With the new lifetime, releasing a bc_prealloc req from\nrpcrdma_req_release() re-adds it to bc_pa_list. The disconnect\nin xprt_rdma_destroy() runs after xprt_destroy_backchannel() has\nalready emptied bc_pa_list, so the drained reqs would otherwise\nleak. xprt_rdma_destroy() now runs xprt_rdma_bc_destroy(xprt, 0)\na second time after the disconnect to reclaim them." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is in the RPC-over-RDMA client (xprtrdma); a remote NFS/RDMA peer delivers Receive completions that invoke rpcrdma_reply_handler() over InfiniBand/RoCE/iWARP, so exploitation is via network protocol traffic from a malicious or compromised server.\nAC:L - For inline Sends using only pre-registered buffers (sc_unmap_count==0), the reply path completes the RPC and returns the req to the free pool before Send completion; a remote peer can reliably trigger this by replying immediately to normal small NFS RPCs.\nPR:N - Exploitation requires no privileges on the victim host; a remote malicious or compromised NFS/RDMA server can send crafted/fast replies over the established RDMA connection to drive the vulnerable completion path.\nUI:N - No end-user interaction is needed at exploit time; once a host uses NFS-over-RDMA, triggering the bug is automatic during ordinary client I/O against the attacker-controlled server.\nS:U - The flaw causes kernel heap UAF/DMA corruption within the NFS client's kernel context and does not by itself cross hypervisor, VM, or sandbox security boundaries.\nC:H - Recycling rpcrdma_req while the HCA may still DMA-read its send buffers is a use-after-free that can expose or leak kernel memory when the slot is reallocated and buffers are reused under active DMA.\nI:H - Premature return of rpcrdma_req to rb_send_bufs while Send WRs are in flight permits heap corruption and typical UAF exploitation paths for arbitrary kernel memory writes or control-flow hijack.\nA:H - Concurrent DMA against freed/reused request buffers can provoke kernel oops/panic or wedged RPC/RDMA transport state, giving high availability impact on NFS-over-RDMA clients." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/xprtrdma/backchannel.c", "net/sunrpc/xprtrdma/rpc_rdma.c", "net/sunrpc/xprtrdma/transport.c", "net/sunrpc/xprtrdma/verbs.c", "net/sunrpc/xprtrdma/xprt_rdma.h" ], "versions": [ { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "740975054a1970c0cf15f70ac39724a064f45847", "status": "affected", "versionType": "git" }, { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "9f3d9b68c1c6c51746e5ecdb52b2e6a2901de37e", "status": "affected", "versionType": "git" }, { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "e7632089523acddcdd8f090ad19e96fb3107b04d", "status": "affected", "versionType": "git" }, { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "53442c7d0c888e51b8bc3da196970a669cc6b294", "status": "affected", "versionType": "git" }, { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "8203f760a72bd39a3b66bc4eff0aa272a99fe22b", "status": "affected", "versionType": "git" }, { "version": "0ab115237025f5e379620bbcd56a02697d07b002", "lessThan": "e786233d2e0bbff9a82e43f02ae3a46ab4b08ec3", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/xprtrdma/backchannel.c", "net/sunrpc/xprtrdma/rpc_rdma.c", "net/sunrpc/xprtrdma/transport.c", "net/sunrpc/xprtrdma/verbs.c", "net/sunrpc/xprtrdma/xprt_rdma.h" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "5.3", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/740975054a1970c0cf15f70ac39724a064f45847" }, { "url": "https://git.kernel.org/stable/c/9f3d9b68c1c6c51746e5ecdb52b2e6a2901de37e" }, { "url": "https://git.kernel.org/stable/c/e7632089523acddcdd8f090ad19e96fb3107b04d" }, { "url": "https://git.kernel.org/stable/c/53442c7d0c888e51b8bc3da196970a669cc6b294" }, { "url": "https://git.kernel.org/stable/c/8203f760a72bd39a3b66bc4eff0aa272a99fe22b" }, { "url": "https://git.kernel.org/stable/c/e786233d2e0bbff9a82e43f02ae3a46ab4b08ec3" } ], "title": "xprtrdma: Decouple req recycling from RPC completion", "x_generator": { "engine": "bippy-1.2.0" } } } }