CVE-2022-50359

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

media: cx88: Fix a null-ptr-deref bug in buffer_prepare()

When the driver calls cx88riscbuffer() to prepare the buffer, the function call may fail, resulting in a empty buffer and null-ptr-deref later in buffer_queue().

The following log can reveal it:

[ 41.822762] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI [ 41.824488] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 41.828027] RIP: 0010:buffer_queue+0xc2/0x500 [ 41.836311] Call Trace: [ 41.836945] __enqueueindriver+0x141/0x360 [ 41.837262] vb2startstreaming+0x62/0x4a0 [ 41.838216] vb2corestreamon+0x1da/0x2c0 [ 41.838516] __vb2initfileio+0x981/0xbc0 [ 41.839141] __vb2performfileio+0xbf9/0x1120 [ 41.840072] vb2fopread+0x20e/0x400 [ 41.840346] v4l2read+0x215/0x290 [ 41.840603] vfsread+0x162/0x4c0

Fix this by checking the return value of cx88riscbuffer()

[hverkuil: fix coding style issues]