{"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"}}}}