Vulnerability CVE-2023-52813
Published: 2024-05-21

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

crypto: pcrypt - Fix hungtask for PADATA_RESET

We found a hungtask bug in test_aead_vec_cfg as follows:

INFO: task cryptomgr_test:391009 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Call trace:
__switch_to+0x98/0xe0
__schedule+0x6c4/0xf40
schedule+0xd8/0x1b4
schedule_timeout+0x474/0x560
wait_for_common+0x368/0x4e0
wait_for_completion+0x20/0x30
wait_for_completion+0x20/0x30
test_aead_vec_cfg+0xab4/0xd50
test_aead+0x144/0x1f0
alg_test_aead+0xd8/0x1e0
alg_test+0x634/0x890
cryptomgr_test+0x40/0x70
kthread+0x1e0/0x220
ret_from_fork+0x10/0x18
Kernel panic - not syncing: hung_task: blocked tasks

For padata_do_parallel, when the return err is 0 or -EBUSY, it will call
wait_for_completion(&wait->completion) in test_aead_vec_cfg. In normal
case, aead_request_complete() will be called in pcrypt_aead_serial and the
return err is 0 for padata_do_parallel. But, when pinst->flags is
PADATA_RESET, the return err is -EBUSY for padata_do_parallel, and it
won't call aead_request_complete(). Therefore, test_aead_vec_cfg will
hung at wait_for_completion(&wait->completion), which will cause
hungtask.

The problem comes as following:
(padata_do_parallel) |
rcu_read_lock_bh(); |
err = -EINVAL; | (padata_replace)
| pinst->flags |= PADATA_RESET;
err = -EBUSY |
if (pinst->flags & PADATA_RESET) |
rcu_read_unlock_bh() |
return err

In order to resolve the problem, we replace the return err -EBUSY with
-EAGAIN, which means parallel_data is changing, and the caller should call
it again.

v3:
remove retry and just change the return err.
v2:
introduce padata_try_do_parallel() in pcrypt_aead_encrypt and
pcrypt_aead_decrypt to solve the hungtask.

 References:
https://git.kernel.org/stable/c/fb2d3a50a8f29a3c66682bb426144f40e32ab818
https://git.kernel.org/stable/c/039fec48e062504f14845124a1a25eb199b2ddc0
https://git.kernel.org/stable/c/c9c1334697301c10e6918d747ed38abfbc0c96e7
https://git.kernel.org/stable/c/e97bf4ada7dddacd184c3e196bd063b0dc71b41d
https://git.kernel.org/stable/c/546c1796ad1ed0d87dab3c4b5156d75819be2316
https://git.kernel.org/stable/c/c55fc098fd9d2dca475b82d00ffbcaf97879d77e
https://git.kernel.org/stable/c/e134f3aba98e6c801a693f540912c2d493718ddf
https://git.kernel.org/stable/c/372636debe852913529b1716f44addd94fff2d28
https://git.kernel.org/stable/c/8f4f68e788c3a7a696546291258bfa5fdb215523
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