cbcvebase.
CVE-2025-21986
published 2025-04-01

CVE-2025-21986: In the Linux kernel, the following vulnerability has been resolved: net: switchdev: Convert blocking notification chain to a raw one A blocking notification…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.14%
3.7th percentile
In the Linux kernel, the following vulnerability has been resolved: net: switchdev: Convert blocking notification chain to a raw one A blocking notification chain uses a read-write semaphore to protect the integrity of the chain. The semaphore is acquired for writing when adding / removing notifiers to / from the chain and acquired for reading when traversing the chain and informing notifiers about an event. In case of the blocking switchdev notification chain, recursive notifications are possible which leads to the semaphore being acquired twice for reading and to lockdep warnings being generated [1]. Specifically, this can happen when the bridge driver processes a SWITCHDEV_BRPORT_UNOFFLOADED event which causes it to emit notifications about deferred events when calling switchdev_deferred_process(). Fix this by converting the notification chain to a raw notification chain in a similar fashion to the netdev notification chain. Protect the chain using the RTNL mutex by acquiring it when modifying the chain. Events are always informed under the RTNL mutex, but add an assertion in call_switchdev_blocking_notifiers() to make sure this is not violated in the future. Maintain the "blocking" prefix as events are always emitted from process context and listeners are allowed to block. [1]: WARNING: possible recursive locking detected 6.14.0-rc4-custom-g079270089484 #1 Not tainted ip/52731 is trying to acquire lock: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0 but task is already holding lock: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock((switchdev_blocking_notif_chain).rwsem); lock((switchdev_blocking_notif_chain).rwsem); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by ip/52731: #0: ffffffff84f795b0 (rtnl_mutex

Affected

23 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.133-1 (bookworm)linux 6.1.133-1 (bookworm)
debianlinux-6.1< linux 6.1.133-1 (bookworm)linux 6.1.133-1 (bookworm)
linuxlinux
linuxlinux
linuxlinux>= 6.1.80 < 6.1.1326.1.132
linuxlinux>= 6.6.19 < 6.6.846.6.84
linuxlinux>= 6.7.7 < 6.86.8
linuxlinux>= 91ac2c79e896b28a4a3a262384689ee6dfeaf083 < af757f5ee3f754c5dceefb05c12ff37cb46fc682af757f5ee3f754c5dceefb05c12ff37cb46fc682
linuxlinux>= a83856bd0c240267a86ce3388f3437d6ba5ac5ca < 1f7d051814e7a0cb1f0717ed5527c1059992129d1f7d051814e7a0cb1f0717ed5527c1059992129d
linuxlinux>= f7a70d650b0b6b0134ccba763d672c8439d9f09b < a597d4b75669ec82c72cbee9fe75a15d04b35b2ba597d4b75669ec82c72cbee9fe75a15d04b35b2b
linuxlinux>= f7a70d650b0b6b0134ccba763d672c8439d9f09b < f9ed3fb50b872bd78bcb01f25087f9e4e25085d8f9ed3fb50b872bd78bcb01f25087f9e4e25085d8
linuxlinux>= f7a70d650b0b6b0134ccba763d672c8439d9f09b < 62531a1effa87bdab12d5104015af72e60d926ff62531a1effa87bdab12d5104015af72e60d926ff
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.1.133-16.1.133-1
linuxlinux_kernel>= 0 < 6.12.20-16.12.20-1
linuxlinux_kernel>= 0 < 6.12.20-16.12.20-1
linuxlinux_kernel>= 0 < 6.8.0-84.846.8.0-84.84
linuxlinux_kernel>= 6.1.80 < 6.1.1326.1.132
linuxlinux_kernel>= 6.13 < 6.13.86.13.8
linuxlinux_kernel>= 6.6.19 < 6.6.846.6.84
linuxlinux_kernel>= 6.7.7 < 6.86.8
linuxlinux_kernel>= 6.8.1 < 6.12.206.12.20

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.9MEDIUM
vendor_ubuntu5.9MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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