{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39932", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.148Z", "datePublished": "2025-10-04T07:30:56.726Z", "dateUpdated": "2026-08-05T12:06:11.549Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:06:11.549Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: let smbd_destroy() call disable_work_sync(&info->post_send_credits_work)\n\nIn smbd_destroy() we may destroy the memory so we better\nwait until post_send_credits_work is no longer pending\nand will never be started again.\n\nI actually just hit the case using rxe:\n\nWARNING: CPU: 0 PID: 138 at drivers/infiniband/sw/rxe/rxe_verbs.c:1032 rxe_post_recv+0x1ee/0x480 [rdma_rxe]\n...\n[ 5305.686979] [ T138] smbd_post_recv+0x445/0xc10 [cifs]\n[ 5305.687135] [ T138] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5305.687149] [ T138] ? __kasan_check_write+0x14/0x30\n[ 5305.687185] [ T138] ? __pfx_smbd_post_recv+0x10/0x10 [cifs]\n[ 5305.687329] [ T138] ? __pfx__raw_spin_lock_irqsave+0x10/0x10\n[ 5305.687356] [ T138] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5305.687368] [ T138] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5305.687378] [ T138] ? _raw_spin_unlock_irqrestore+0x11/0x60\n[ 5305.687389] [ T138] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5305.687399] [ T138] ? get_receive_buffer+0x168/0x210 [cifs]\n[ 5305.687555] [ T138] smbd_post_send_credits+0x382/0x4b0 [cifs]\n[ 5305.687701] [ T138] ? __pfx_smbd_post_send_credits+0x10/0x10 [cifs]\n[ 5305.687855] [ T138] ? __pfx___schedule+0x10/0x10\n[ 5305.687865] [ T138] ? __pfx__raw_spin_lock_irq+0x10/0x10\n[ 5305.687875] [ T138] ? queue_delayed_work_on+0x8e/0xa0\n[ 5305.687889] [ T138] process_one_work+0x629/0xf80\n[ 5305.687908] [ T138] ? srso_alias_return_thunk+0x5/0xfbef5\n[ 5305.687917] [ T138] ? __kasan_check_write+0x14/0x30\n[ 5305.687933] [ T138] worker_thread+0x87f/0x1570\n...\n\nIt means rxe_post_recv was called after rdma_destroy_qp().\nThis happened because put_receive_buffer() was triggered\nby ib_drain_qp() and called:\nqueue_work(info->workqueue, &info->post_send_credits_work);" } ], "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 vulnerable teardown path is the client's SMB Direct (RDMA) transport, driven entirely by the remote SMB server peer over iWARP/RoCE/IB — the peer triggers the disconnect that enters `smbd_destroy()` via `cifs_reconnect()`/`smbd_reconnect()` and controls the receive-credit traffic that requeues `post_send_credits_work`. This matches the established scoring of other client-side smbdirect flaws (e.g. CVE-2026-31609, CVE-2026-31535) as network-reachable.\nAC:L - The attacker owns both sides of the race: it initiates the RDMA disconnect that starts `smbd_destroy()`, it controls how many receive buffers are outstanding (and therefore how many `put_receive_buffer()` → `queue_work()` requeues `ib_drain_qp()` flushes), and it can force reconnect cycles indefinitely until it wins. The window is not narrow — the reporter hit it during ordinary rxe testing, and the worker's status check is a TOCTOU that a preempted worker bypasses without any signal or unusual state.\nPR:N - The SMB Direct transport connect/teardown and credit machinery sits below SMB session setup, so no credentials, capability, or account on the target are validated anywhere on the path to `smbd_post_send_credits()`. The remote peer needs no privileges on the client to reset the connection and drive the teardown.\nUI:N - Against an already-established SMB Direct mount — persistent deployment state, not participation in the compromise — the attacker completes the whole sequence by resetting the RDMA connection; the client's demultiplex thread enters `smbd_reconnect()` → `smbd_destroy()` automatically with no victim action.\nS:U - The freed QP, protection domain and receive buffers are all kernel-internal objects belonging to the same security authority as the faulting code. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free of the `ib_qp` freed by `rdma_destroy_qp()`, whose contents are read back by `ib_post_recv()`/`ib_post_send()` (`qp->device`, `qp->valid`, queue pointers) along with a stale `sc->ib.pd->local_dma_lkey`; reclaiming that slab lets an attacker read and exfiltrate kernel memory, and stale DMA mappings can expose freed receive buffers.\nI:H - `ib_post_recv()` dispatches through `qp->device->ops.post_recv` — a function pointer loaded from freed memory — giving a control-flow hijack primitive once the QP slab is sprayed, and the driver additionally writes a WQE and producer index into the freed ring, yielding a write primitive into reclaimed memory.\nA:H - The observed result is a kernel WARN/oops inside the workqueue worker, and after `sc->ib.qp = NULL` the same path is an outright NULL dereference; either panics the machine under `panic_on_oops` and otherwise wedges the SMB Direct connection, and the attacker can retrigger it on every reconnect." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/smbdirect.c" ], "versions": [ { "version": "f198186aa9bbd60fae7a2061f4feec614d880299", "lessThan": "6ae90a2baf923e85eb037b636aa641250bf4220f", "status": "affected", "versionType": "git" }, { "version": "f198186aa9bbd60fae7a2061f4feec614d880299", "lessThan": "3fabb1236f2e3ad78d531be0a4ad9f4a4ccdda87", "status": "affected", "versionType": "git" }, { "version": "f198186aa9bbd60fae7a2061f4feec614d880299", "lessThan": "d9dcbbcf9145b68aa85c40947311a6907277e097", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/smbdirect.c" ], "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.49", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.9", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "4.16", "versionEndExcluding": "6.12.49" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.16.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/6ae90a2baf923e85eb037b636aa641250bf4220f" }, { "url": "https://git.kernel.org/stable/c/3fabb1236f2e3ad78d531be0a4ad9f4a4ccdda87" }, { "url": "https://git.kernel.org/stable/c/d9dcbbcf9145b68aa85c40947311a6907277e097" } ], "title": "smb: client: let smbd_destroy() call disable_work_sync(&info->post_send_credits_work)", "x_generator": { "engine": "bippy-1.2.0" } } } }