# CVE-2022-50773: CVE-2022-50773

Status: published. Published: 2025-12-24. Updated: 2026-11-10.

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

ALSA: mts64: fix possible null-ptr-defer in snd_mts64_interrupt

I got a null-ptr-defer error report when I do the following tests
on the qemu platform:

make defconfig and CONFIG_PARPORT=m, CONFIG_PARPORT_PC=m,
CONFIG_SND_MTS64=m

Then making test scripts:
cat>test_mod1.sh<<EOF
modprobe snd-mts64
modprobe snd-mts64
EOF

Executing the script, perhaps several times, we will get a null-ptr-defer
report, as follow:

syzkaller:~# ./test_mod.sh
snd_mts64: probe of snd_mts64.0 failed with error -5
modprobe: ERROR: could not insert 'snd_mts64': No such device
 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor write access in kernel mode
 #PF: error_code(0x0002) - not-present page
 PGD 0 P4D 0
 Oops: 0002 [#1] PREEMPT SMP PTI
 CPU: 0 PID: 205 Comm: modprobe Not tainted 6.1.0-rc8-00588-g76dcd734eca2 #6
 Call Trace:
  <IRQ>
  snd_mts64_interrupt+0x24/0xa0 [snd_mts64]
  parport_irq_handler+0x37/0x50 [parport]
  __handle_irq_event_percpu+0x39/0x190
  handle_irq_event_percpu+0xa/0x30
  handle_irq_event+0x2f/0x50
  handle_edge_irq+0x99/0x1b0
  __common_interrupt+0x5d/0x100
  common_interrupt+0xa0/0xc0
  </IRQ>
  <TASK>
  asm_common_interrupt+0x22/0x40
 RIP: 0010:_raw_write_unlock_irqrestore+0x11/0x30
  parport_claim+0xbd/0x230 [parport]
  snd_mts64_probe+0x14a/0x465 [snd_mts64]
  platform_probe+0x3f/0xa0
  really_probe+0x129/0x2c0
  __driver_probe_device+0x6d/0xc0
  driver_probe_device+0x1a/0xa0
  __device_attach_driver+0x7a/0xb0
  bus_for_each_drv+0x62/0xb0
  __device_attach+0xe4/0x180
  bus_probe_device+0x82/0xa0
  device_add+0x550/0x920
  platform_device_add+0x106/0x220
  snd_mts64_attach+0x2e/0x80 [snd_mts64]
  port_check+0x14/0x20 [parport]
  bus_for_each_dev+0x6e/0xc0
  __parport_register_driver+0x7c/0xb0 [parport]
  snd_mts64_module_init+0x31/0x1000 [snd_mts64]
  do_one_initcall+0x3c/0x1f0
  do_init_module+0x46/0x1c6
  load_module+0x1d8d/0x1e10
  __do_sys_finit_module+0xa2/0xf0
  do_syscall_64+0x37/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
  </TASK>
 Kernel panic - not syncing: Fatal exception in interrupt
 Rebooting in 1 seconds..

The mts wa not initialized during interrupt,  we add check for
mts to fix this bug.

## Remediation

No remediation reported in collected sources

## Affected products and versions

Not reported in collected sources.

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/0649129359219ce6ff380ec401f87308485c6ae3 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/06ec592389f2be3199779ab823c4323dcfd2121f (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/1a763c748acd5540ccc43306c57c9c6c5fb60884 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/250eed7b9994d79f9c409f954dbd08e88f5afd83 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/7e91667db38abb056da5a496d40fbd044c66bed2 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/b471fe61da523a15e4cb60fa81f5a2377e4bad98 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/c7e9624d90bf20f1eed6b228949396d614b94020 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/cba633b24a98d957e8190ef8bc4d4cdb4f6e9313 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/cf2ea3c86ad90d63d1c572b43e1ca9276b0357ad (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50773; retrieved 2026-11-10; source updated 2026-11-10

Revision: 1b2079fbdf8d579cb1165e632c378e901a28f1d209b50f9fdd27a671de1f6436

Canonical: https://y2.dev/cve/CVE-2022-50773

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