{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2025-21986", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.800Z", "datePublished": "2025-04-01T15:47:12.636Z", "dateUpdated": "2025-05-04T13:06:50.853Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-05-04T13:06:50.853Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: switchdev: Convert blocking notification chain to a raw one\n\nA blocking notification chain uses a read-write semaphore to protect the\nintegrity of the chain. The semaphore is acquired for writing when\nadding / removing notifiers to / from the chain and acquired for reading\nwhen traversing the chain and informing notifiers about an event.\n\nIn case of the blocking switchdev notification chain, recursive\nnotifications are possible which leads to the semaphore being acquired\ntwice for reading and to lockdep warnings being generated [1].\n\nSpecifically, this can happen when the bridge driver processes a\nSWITCHDEV_BRPORT_UNOFFLOADED event which causes it to emit notifications\nabout deferred events when calling switchdev_deferred_process().\n\nFix this by converting the notification chain to a raw notification\nchain in a similar fashion to the netdev notification chain. Protect\nthe chain using the RTNL mutex by acquiring it when modifying the chain.\nEvents are always informed under the RTNL mutex, but add an assertion in\ncall_switchdev_blocking_notifiers() to make sure this is not violated in\nthe future.\n\nMaintain the \"blocking\" prefix as events are always emitted from process\ncontext and listeners are allowed to block.\n\n[1]:\nWARNING: possible recursive locking detected\n6.14.0-rc4-custom-g079270089484 #1 Not tainted\n--------------------------------------------\nip/52731 is trying to acquire lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nbut task is already holding lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nother info that might help us debug this:\nPossible unsafe locking scenario:\nCPU0\n----\nlock((switchdev_blocking_notif_chain).rwsem);\nlock((switchdev_blocking_notif_chain).rwsem);\n\n*** DEADLOCK ***\nMay be due to missing lock nesting notation\n3 locks held by ip/52731:\n #0: ffffffff84f795b0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x727/0x1dc0\n #1: ffffffff8731f628 (&net->rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x790/0x1dc0\n #2: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nstack backtrace:\n...\n? __pfx_down_read+0x10/0x10\n? __pfx_mark_lock+0x10/0x10\n? __pfx_switchdev_port_attr_set_deferred+0x10/0x10\nblocking_notifier_call_chain+0x58/0xa0\nswitchdev_port_attr_notify.constprop.0+0xb3/0x1b0\n? __pfx_switchdev_port_attr_notify.constprop.0+0x10/0x10\n? mark_held_locks+0x94/0xe0\n? switchdev_deferred_process+0x11a/0x340\nswitchdev_port_attr_set_deferred+0x27/0xd0\nswitchdev_deferred_process+0x164/0x340\nbr_switchdev_port_unoffload+0xc8/0x100 [bridge]\nbr_switchdev_blocking_event+0x29f/0x580 [bridge]\nnotifier_call_chain+0xa2/0x440\nblocking_notifier_call_chain+0x6e/0xa0\nswitchdev_bridge_port_unoffload+0xde/0x1a0\n..."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/switchdev/switchdev.c"], "versions": [{"version": "91ac2c79e896b28a4a3a262384689ee6dfeaf083", "lessThan": "af757f5ee3f754c5dceefb05c12ff37cb46fc682", "status": "affected", "versionType": "git"}, {"version": "a83856bd0c240267a86ce3388f3437d6ba5ac5ca", "lessThan": "1f7d051814e7a0cb1f0717ed5527c1059992129d", "status": "affected", "versionType": "git"}, {"version": "f7a70d650b0b6b0134ccba763d672c8439d9f09b", "lessThan": "a597d4b75669ec82c72cbee9fe75a15d04b35b2b", "status": "affected", "versionType": "git"}, {"version": "f7a70d650b0b6b0134ccba763d672c8439d9f09b", "lessThan": "f9ed3fb50b872bd78bcb01f25087f9e4e25085d8", "status": "affected", "versionType": "git"}, {"version": "f7a70d650b0b6b0134ccba763d672c8439d9f09b", "lessThan": "62531a1effa87bdab12d5104015af72e60d926ff", "status": "affected", "versionType": "git"}, {"version": "a7589eca09929c3cc2a62950ef7f40bcc58afe3a", "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/switchdev/switchdev.c"], "versions": [{"version": "6.8", "status": "affected"}, {"version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.132", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.84", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.20", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.13.8", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.14", "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": "6.1.80", "versionEndExcluding": "6.1.132"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.19", "versionEndExcluding": "6.6.84"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.20"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.13.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.14"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7.7"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/af757f5ee3f754c5dceefb05c12ff37cb46fc682"}, {"url": "https://git.kernel.org/stable/c/1f7d051814e7a0cb1f0717ed5527c1059992129d"}, {"url": "https://git.kernel.org/stable/c/a597d4b75669ec82c72cbee9fe75a15d04b35b2b"}, {"url": "https://git.kernel.org/stable/c/f9ed3fb50b872bd78bcb01f25087f9e4e25085d8"}, {"url": "https://git.kernel.org/stable/c/62531a1effa87bdab12d5104015af72e60d926ff"}], "title": "net: switchdev: Convert blocking notification chain to a raw one", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: switchdev: Convert blocking notification chain to a raw one\n\nA blocking notification chain uses a read-write semaphore to protect the\nintegrity of the chain. The semaphore is acquired for writing when\nadding / removing notifiers to / from the chain and acquired for reading\nwhen traversing the chain and informing notifiers about an event.\n\nIn case of the blocking switchdev notification chain, recursive\nnotifications are possible which leads to the semaphore being acquired\ntwice for reading and to lockdep warnings being generated [1].\n\nSpecifically, this can happen when the bridge driver processes a\nSWITCHDEV_BRPORT_UNOFFLOADED event which causes it to emit notifications\nabout deferred events when calling switchdev_deferred_process().\n\nFix this by converting the notification chain to a raw notification\nchain in a similar fashion to the netdev notification chain. Protect\nthe chain using the RTNL mutex by acquiring it when modifying the chain.\nEvents are always informed under the RTNL mutex, but add an assertion in\ncall_switchdev_blocking_notifiers() to make sure this is not violated in\nthe future.\n\nMaintain the \"blocking\" prefix as events are always emitted from process\ncontext and listeners are allowed to block.\n\n[1]:\nWARNING: possible recursive locking detected\n6.14.0-rc4-custom-g079270089484 #1 Not tainted\n--------------------------------------------\nip/52731 is trying to acquire lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nbut task is already holding lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nother info that might help us debug this:\nPossible unsafe locking scenario:\nCPU0\n----\nlock((switchdev_blocking_notif_chain).rwsem);\nlock((switchdev_blocking_notif_chain).rwsem);\n\n*** DEADLOCK ***\nMay be due to missing lock nesting notation\n3 locks held by ip/52731:\n #0: ffffffff84f795b0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x727/0x1dc0\n #1: ffffffff8731f628 (&net->rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x790/0x1dc0\n #2: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\n\nstack backtrace:\n...\n? __pfx_down_read+0x10/0x10\n? __pfx_mark_lock+0x10/0x10\n? __pfx_switchdev_port_attr_set_deferred+0x10/0x10\nblocking_notifier_call_chain+0x58/0xa0\nswitchdev_port_attr_notify.constprop.0+0xb3/0x1b0\n? __pfx_switchdev_port_attr_notify.constprop.0+0x10/0x10\n? mark_held_locks+0x94/0xe0\n? switchdev_deferred_process+0x11a/0x340\nswitchdev_port_attr_set_deferred+0x27/0xd0\nswitchdev_deferred_process+0x164/0x340\nbr_switchdev_port_unoffload+0xc8/0x100 [bridge]\nbr_switchdev_blocking_event+0x29f/0x580 [bridge]\nnotifier_call_chain+0xa2/0x440\nblocking_notifier_call_chain+0x6e/0xa0\nswitchdev_bridge_port_unoffload+0xde/0x1a0\n..."}], "id": "CVE-2025-21986", "lastModified": "2025-04-01T20:26:01.990", "metrics": {}, "published": "2025-04-01T16:15:30.010", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1f7d051814e7a0cb1f0717ed5527c1059992129d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/62531a1effa87bdab12d5104015af72e60d926ff"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a597d4b75669ec82c72cbee9fe75a15d04b35b2b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/af757f5ee3f754c5dceefb05c12ff37cb46fc682"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f9ed3fb50b872bd78bcb01f25087f9e4e25085d8"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{"bugzilla": {"description": "kernel: net: switchdev: Convert blocking notification chain to a raw one", "id": "2356607", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2356607"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-667->CWE-833", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet: switchdev: Convert blocking notification chain to a raw one\nA blocking notification chain uses a read-write semaphore to protect the\nintegrity of the chain. The semaphore is acquired for writing when\nadding / removing notifiers to / from the chain and acquired for reading\nwhen traversing the chain and informing notifiers about an event.\nIn case of the blocking switchdev notification chain, recursive\nnotifications are possible which leads to the semaphore being acquired\ntwice for reading and to lockdep warnings being generated [1].\nSpecifically, this can happen when the bridge driver processes a\nSWITCHDEV_BRPORT_UNOFFLOADED event which causes it to emit notifications\nabout deferred events when calling switchdev_deferred_process().\nFix this by converting the notification chain to a raw notification\nchain in a similar fashion to the netdev notification chain. Protect\nthe chain using the RTNL mutex by acquiring it when modifying the chain.\nEvents are always informed under the RTNL mutex, but add an assertion in\ncall_switchdev_blocking_notifiers() to make sure this is not violated in\nthe future.\nMaintain the \"blocking\" prefix as events are always emitted from process\ncontext and listeners are allowed to block.\n[1]:\nWARNING: possible recursive locking detected\n6.14.0-rc4-custom-g079270089484 #1 Not tainted\n--------------------------------------------\nip/52731 is trying to acquire lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\nbut task is already holding lock:\nffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\nother info that might help us debug this:\nPossible unsafe locking scenario:\nCPU0\n----\nlock((switchdev_blocking_notif_chain).rwsem);\nlock((switchdev_blocking_notif_chain).rwsem);\n*** DEADLOCK ***\nMay be due to missing lock nesting notation\n3 locks held by ip/52731:\n#0: ffffffff84f795b0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x727/0x1dc0\n#1: ffffffff8731f628 (&net->rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x790/0x1dc0\n#2: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0\nstack backtrace:\n...\n? __pfx_down_read+0x10/0x10\n? __pfx_mark_lock+0x10/0x10\n? __pfx_switchdev_port_attr_set_deferred+0x10/0x10\nblocking_notifier_call_chain+0x58/0xa0\nswitchdev_port_attr_notify.constprop.0+0xb3/0x1b0\n? __pfx_switchdev_port_attr_notify.constprop.0+0x10/0x10\n? mark_held_locks+0x94/0xe0\n? switchdev_deferred_process+0x11a/0x340\nswitchdev_port_attr_set_deferred+0x27/0xd0\nswitchdev_deferred_process+0x164/0x340\nbr_switchdev_port_unoffload+0xc8/0x100 [bridge]\nbr_switchdev_blocking_event+0x29f/0x580 [bridge]\nnotifier_call_chain+0xa2/0x440\nblocking_notifier_call_chain+0x6e/0xa0\nswitchdev_bridge_port_unoffload+0xde/0x1a0\n..."], "name": "CVE-2025-21986", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-01T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-21986\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21986\nhttps://lore.kernel.org/linux-cve-announce/2025040149-CVE-2025-21986-6729@gregkh/T"], "threat_severity": "Low"}