ALSA: pcm: oss: Fix data race at accessing runtime.oss.trigger

Overview

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

ALSA: pcm: oss: Fix data race at accessing runtime.oss.trigger

Currently the runtime.oss.trigger field may be accessed concurrently without protection, which may lead to the data race. And, in this case, it may lead to more severe problem because it's a bit field; as writing the data, it may overwrite other bit fields as well, which confuses the operation completely, as spotted by fuzzing.

Fix it by covering runtime.oss.trigger bit fled also with the existing params_lock mutex in both snd_pcm_oss_get_trigger() and snd_pcm_oss_poll().

Affected

• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c937a494901df8fbfaa5037a5883a7cd44282ea8
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 49f9d048845be874df7997e4b1ce662de450c4b6
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ac3e9b55b7da6f0be51720bd330a0edc1a8b61f1
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6b01c1bc9a4748ab37548a700a8aaff910e298e6
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 901ac0ff15edf9503162e2cf6579bd11a30f1ed4
• Linux 2.6.12

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.