comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large The handling of the `COMEDI_INSNLIST` ioctl allocates a kernel buffer to hold the array of `struct comedi_insn`, getting the length from the `n_insns` member of the `struct comedi_insnlist` supplied by the user. The allocation will fail with a WARNING and a stack dump if it is too large. Avoid that by failing with an `-EINVAL` error if the supplied `n_insns` value is unreasonable. Define the limit on the `n_insns` value in the `MAX_INSNS` macro. Set this to the same value as `MAX_SAMPLES` (65536), which is the maximum allowed sum of the values of the member `n` in the array of `struct comedi_insn`, and sensible comedi instructions will have an `n` of at least 1.

References

• https://git.kernel.org/stable/c/454d732dfd0aef7d7aa950c409215ca06d717e93
• https://git.kernel.org/stable/c/c68257588e87f45530235701a42496b7e9e56adb
• https://git.kernel.org/stable/c/69dc06b9514522de532e997a21d035cd29b0db44
• https://git.kernel.org/stable/c/d4c73ce13f5b5a0fe0319f1f352ff602f0ace8e3
• https://git.kernel.org/stable/c/c9d3d9667443caafa804cd07940aeaef8e53aa90
• https://git.kernel.org/stable/c/992d600f284e719242a434166e86c1999649b71c
• https://git.kernel.org/stable/c/e3b8322cc8081d142ee4c1a43e1d702bdba1ed76
• https://git.kernel.org/stable/c/08ae4b20f5e82101d77326ecab9089e110f224cc