CVE-2022-49292 Information

Description

In the Linux kernel the following vulnerability has been resolved:

ALSA: oss: Fix PCM OSS buffer allocation overflow

We’ve got syzbot reports hitting INT_MAX overflow at vmalloc() allocation that is called from snd_pcm_plug_alloc(). Although we apply the restrictions to input parameters it’s based only on the hw_params of the underlying PCM device. Since the PCM OSS layer allocates a temporary buffer for the data conversion the size may become unexpectedly large when more channels or higher rates is given; in the reported case it went over INT_MAX hence it hits WARN_ON().

This patch is an attempt to avoid such an overflow and an allocation for too large buffers. First off it adds the limit of 1MB as the upper bound for period bytes. This must be large enough for all use cases and we really don’t want to handle a larger temporary buffer than this size. The size check is performed at two places where the original period bytes is calculated and where the plugin buffer size is calculated.

In addition the driver uses array_size() and array3_size() for multiplications to catch overflows for the converted period size and buffer bytes.

Reference

https://git.kernel.org/stable/c/0c4190b41a69990666b4000999e27f8f1b2a426b https://git.kernel.org/stable/c/5ce74ff7059341d8b2f4d01c3383491df63d1898 https://git.kernel.org/stable/c/7a40cbf3579a8e14849ba7ce46309c1992658d2b https://git.kernel.org/stable/c/a63af1baf0a5e11827db60e3127f87e437cab6e5 https://git.kernel.org/stable/c/e74a069c6a7bb505f3ade141dddf85f4b0b5145a https://git.kernel.org/stable/c/efb6402c3c4a7c26d97c92d70186424097b6e366 https://git.kernel.org/stable/c/fb08bf99195a87c798bc8ae1357337a981faeade