CVE-2021-47468

In the Linux kernel, the following vulnerability has been resolved:

isdn: mISDN: Fix sleeping function called from invalid context

The driver can call card->isac.release() function from an atomic context.

Fix this by calling this function after releasing the lock.

The following log reveals it:

[ 44.168226 ] BUG: sleeping function called from invalid context at kernel/workqueue.c:3018 [ 44.168941 ] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 5475, name: modprobe [ 44.169574 ] INFO: lockdep is turned off. [ 44.169899 ] irq event stamp: 0 [ 44.170160 ] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [ 44.170627 ] hardirqs last disabled at (0): [] copy_process+0x132d/0x3e00 [ 44.171240 ] softirqs last enabled at (0): [] copy_process+0x135a/0x3e00 [ 44.171852 ] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 44.172318 ] Preemption disabled at: [ 44.172320 ] [] nj_release+0x69/0x500 [netjet] [ 44.174441 ] Call Trace: [ 44.174630 ] dump_stack_lvl+0xa8/0xd1 [ 44.174912 ] dump_stack+0x15/0x17 [ 44.175166 ] ___might_sleep+0x3a2/0x510 [ 44.175459 ] ? nj_release+0x69/0x500 [netjet] [ 44.175791 ] __might_sleep+0x82/0xe0 [ 44.176063 ] ? start_flush_work+0x20/0x7b0 [ 44.176375 ] start_flush_work+0x33/0x7b0 [ 44.176672 ] ? trace_irq_enable_rcuidle+0x85/0x170 [ 44.177034 ] ? kasan_quarantine_put+0xaa/0x1f0 [ 44.177372 ] ? kasan_quarantine_put+0xaa/0x1f0 [ 44.177711 ] __flush_work+0x11a/0x1a0 [ 44.177991 ] ? flush_work+0x20/0x20 [ 44.178257 ] ? lock_release+0x13c/0x8f0 [ 44.178550 ] ? __kasan_check_write+0x14/0x20 [ 44.178872 ] ? do_raw_spin_lock+0x148/0x360 [ 44.179187 ] ? read_lock_is_recursive+0x20/0x20 [ 44.179530 ] ? __kasan_check_read+0x11/0x20 [ 44.179846 ] ? do_raw_spin_unlock+0x55/0x900 [ 44.180168 ] ? ____kasan_slab_free+0x116/0x140 [ 44.180505 ] ? _raw_spin_unlock_irqrestore+0x41/0x60 [ 44.180878 ] ? skb_queue_purge+0x1a3/0x1c0 [ 44.181189 ] ? kfree+0x13e/0x290 [ 44.181438 ] flush_work+0x17/0x20 [ 44.181695 ] mISDN_freedchannel+0xe8/0x100 [ 44.182006 ] isac_release+0x210/0x260 [mISDNipac] [ 44.182366 ] nj_release+0xf6/0x500 [netjet] [ 44.182685 ] nj_remove+0x48/0x70 [netjet] [ 44.182989 ] pci_device_remove+0xa9/0x250

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/37e4f57b22cc5ebb3f80cf0f74fdeb487f082367
• https://git.kernel.org/stable/c/4054b869dc263228d30a4755800b78f0f2ba0c89
• https://git.kernel.org/stable/c/6510e80a0b81b5d814e3aea6297ba42f5e76f73c
• https://git.kernel.org/stable/c/6f95c97e0f9d6eb39c3f2cb45e8fa4268d1b372b
• https://git.kernel.org/stable/c/9f591cbdbed3d7822b2bdba89b34a6d7b434317d
• https://git.kernel.org/stable/c/a5b34409d3fc52114c828be4adbc30744fa3258b
• https://git.kernel.org/stable/c/ef269a8808cb1759245a98a7fe16fceaebad894c
• https://git.kernel.org/stable/c/f5966ba53013149bcf94e1536644a958dd00a026
• https://git.kernel.org/stable/c/37e4f57b22cc5ebb3f80cf0f74fdeb487f082367
• https://git.kernel.org/stable/c/4054b869dc263228d30a4755800b78f0f2ba0c89
• https://git.kernel.org/stable/c/6510e80a0b81b5d814e3aea6297ba42f5e76f73c
• https://git.kernel.org/stable/c/6f95c97e0f9d6eb39c3f2cb45e8fa4268d1b372b
• https://git.kernel.org/stable/c/9f591cbdbed3d7822b2bdba89b34a6d7b434317d
• https://git.kernel.org/stable/c/a5b34409d3fc52114c828be4adbc30744fa3258b
• https://git.kernel.org/stable/c/ef269a8808cb1759245a98a7fe16fceaebad894c
• https://git.kernel.org/stable/c/f5966ba53013149bcf94e1536644a958dd00a026