media: pvrusb2: fix array-index-out-of-bounds in pvr2_i2c_core_init

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: media: pvrusb2: fix array-index-out-of-bounds in pvr2_i2c_core_init Syzbot reported that -1 is used as array index. The problem was in missing validation check. hdw->unit_number is initialized with -1 and then if init table walk fails this value remains unchanged. Since code blindly uses this member for array indexing adding sanity check is the easiest fix for that. hdw->workpoll initialization moved upper to prevent warning in __flush_work.

References

• https://git.kernel.org/stable/c/4351bfe36aba9fa7dc9d68d498d25d41a0f45e67
• https://git.kernel.org/stable/c/2e004fe914b243db41fa96f9e583385f360ea58e
• https://git.kernel.org/stable/c/a3660e06675bccec4bf149c7229ea1d491ba10d7
• https://git.kernel.org/stable/c/1310fc3538dcc375a2f46ef0a438512c2ca32827
• https://git.kernel.org/stable/c/a3304766d9384886e6d3092c776273526947a2e9
• https://git.kernel.org/stable/c/3309c2c574e13b21b44729f5bdbf21f60189b79a
• https://git.kernel.org/stable/c/f99a8b1ec0eddc2931aeaa4f490277a15b39f511
• https://git.kernel.org/stable/c/24e807541e4a9263ed928e6ae3498de3ad43bd1e
• https://git.kernel.org/stable/c/471bec68457aaf981add77b4f590d65dd7da1059