{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-46925", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-25T13:45:52.719Z", "datePublished": "2024-02-27T09:43:55.445Z", "dateUpdated": "2026-08-05T08:45:07.408Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:45:07.408Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix kernel panic caused by race of smc_sock\n\nA crash occurs when smc_cdc_tx_handler() tries to access smc_sock\nbut smc_release() has already freed it.\n\n[ 4570.695099] BUG: unable to handle page fault for address: 000000002eae9e88\n[ 4570.696048] #PF: supervisor write access in kernel mode\n[ 4570.696728] #PF: error_code(0x0002) - not-present page\n[ 4570.697401] PGD 0 P4D 0\n[ 4570.697716] Oops: 0002 [#1] PREEMPT SMP NOPTI\n[ 4570.698228] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.16.0-rc4+ #111\n[ 4570.699013] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 8c24b4c 04/0\n[ 4570.699933] RIP: 0010:_raw_spin_lock+0x1a/0x30\n<...>\n[ 4570.711446] Call Trace:\n[ 4570.711746] \n[ 4570.711992] smc_cdc_tx_handler+0x41/0xc0\n[ 4570.712470] smc_wr_tx_tasklet_fn+0x213/0x560\n[ 4570.712981] ? smc_cdc_tx_dismisser+0x10/0x10\n[ 4570.713489] tasklet_action_common.isra.17+0x66/0x140\n[ 4570.714083] __do_softirq+0x123/0x2f4\n[ 4570.714521] irq_exit_rcu+0xc4/0xf0\n[ 4570.714934] common_interrupt+0xba/0xe0\n\nThough smc_cdc_tx_handler() checked the existence of smc connection,\nsmc_release() may have already dismissed and released the smc socket\nbefore smc_cdc_tx_handler() further visits it.\n\nsmc_cdc_tx_handler() |smc_release()\nif (!conn) |\n |\n |smc_cdc_tx_dismiss_slots()\n | smc_cdc_tx_dismisser()\n |\n |sock_put(&smc->sk) <- last sock_put,\n | smc_sock freed\nbh_lock_sock(&smc->sk) (panic) |\n\nTo make sure we won't receive any CDC messages after we free the\nsmc_sock, add a refcount on the smc_connection for inflight CDC\nmessage(posted to the QP but haven't received related CQE), and\ndon't release the smc_connection until all the inflight CDC messages\nhaven been done, for both success or failed ones.\n\nUsing refcount on CDC messages brings another problem: when the link\nis going to be destroyed, smcr_link_clear() will reset the QP, which\nthen remove all the pending CQEs related to the QP in the CQ. To make\nsure all the CQEs will always come back so the refcount on the\nsmc_connection can always reach 0, smc_ib_modify_qp_reset() was replaced\nby smc_ib_modify_qp_error().\nAnd remove the timeout in smc_wr_tx_wait_no_pending_sends() since we\nneed to wait for all pending WQEs done, or we may encounter use-after-\nfree when handling CQEs.\n\nFor IB device removal routine, we need to wait for all the QPs on that\ndevice been destroyed before we can destroy CQs on the device, or\nthe refcount on smc_connection won't reach 0 and smc_sock cannot be\nreleased." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached through AF_SMC socket syscalls (send/close) on an established SMC-R connection; it is not triggered by unsolicited remote packet parsing alone, so Attack Vector is Local.\nAC:L - The attacker controls both sides of the race by posting CDC TX work (send) and freeing the socket (close), and can retry until the TX completion tasklet hits the dangling smc_sock, so complexity is Low.\nPR:L - socket(AF_SMC) has no capability check, so any unprivileged local user on a host with SMC/RoCE can open SMC-R connections and trigger the path.\nUI:N - Exploitation requires only the attacker's own socket operations; no separate victim user action is needed.\nS:U - This is a standard in-kernel UAF/privilege-escalation class issue within the host kernel's authority, with no VM/IOMMU boundary crossing.\nC:H - The race frees smc_sock while smc_cdc_tx_handler still holds a pointer to it; reclaiming that object yields a classic UAF read primitive, so Confidentiality is High.\nI:H - The handler writes through the freed sock (bh_lock_sock spinlock and connection cursor/space updates), enabling heap corruption and control-flow hijacking via UAF, so Integrity is High.\nA:H - The demonstrated outcome is a kernel oops/page-fault panic in softirq when the freed sock is accessed, so Availability is High." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/smc/smc.h", "net/smc/smc_cdc.c", "net/smc/smc_cdc.h", "net/smc/smc_core.c", "net/smc/smc_ib.c", "net/smc/smc_ib.h", "net/smc/smc_wr.c", "net/smc/smc_wr.h" ], "versions": [ { "version": "5f08318f617b05b6ee389d8bd174c7af921ebf19", "lessThan": "e8a5988a85c719ce7205cb00dcf0716dcf611332", "status": "affected", "versionType": "git" }, { "version": "5f08318f617b05b6ee389d8bd174c7af921ebf19", "lessThan": "b85f751d71ae8e2a15e9bda98852ea9af35282eb", "status": "affected", "versionType": "git" }, { "version": "5f08318f617b05b6ee389d8bd174c7af921ebf19", "lessThan": "349d43127dac00c15231e8ffbcaabd70f7b0e544", "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/smc/smc.h", "net/smc/smc_cdc.c", "net/smc/smc_cdc.h", "net/smc/smc_core.c", "net/smc/smc_ib.c", "net/smc/smc_ib.h", "net/smc/smc_wr.c", "net/smc/smc_wr.h" ], "versions": [ { "version": "4.11", "status": "affected" }, { "version": "0", "lessThan": "4.11", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.90", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.13", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.16", "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": "4.11", "versionEndExcluding": "5.10.90" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "5.15.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "5.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e8a5988a85c719ce7205cb00dcf0716dcf611332" }, { "url": "https://git.kernel.org/stable/c/b85f751d71ae8e2a15e9bda98852ea9af35282eb" }, { "url": "https://git.kernel.org/stable/c/349d43127dac00c15231e8ffbcaabd70f7b0e544" } ], "title": "net/smc: fix kernel panic caused by race of smc_sock", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "problemTypes": [ { "descriptions": [ { "type": "CWE", "cweId": "CWE-362", "lang": "en", "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')" } ] } ], "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 4.7, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "timestamp": "2024-02-27T14:30:40.812518Z", "id": "CVE-2021-46925", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-10-29T13:48:24.020Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:17:42.919Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/e8a5988a85c719ce7205cb00dcf0716dcf611332", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/b85f751d71ae8e2a15e9bda98852ea9af35282eb", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/349d43127dac00c15231e8ffbcaabd70f7b0e544", "tags": [ "x_transferred" ] } ] } ] } }