HID: core: Harden s32ton() against conversion to 0 bits

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: HID: core: Harden s32ton() against conversion to 0 bits Testing by the syzbot fuzzer showed that the HID core gets a shift-out-of-bounds exception when it tries to convert a 32-bit quantity to a 0-bit quantity. Ideally this should never occur, but there are buggy devices and some might have a report field with size set to zero; we shouldn't reject the report or the device just because of that. Instead, harden the s32ton() routine so that it returns a reasonable result instead of crashing when it is called with the number of bits set to 0 -- the same as what snto32() does.

References

• https://git.kernel.org/stable/c/6cdf6c708717c5c6897d0800a1793e83757c7491
• https://git.kernel.org/stable/c/eeeaba737919bdce9885e2a00ac2912f61a3684d
• https://git.kernel.org/stable/c/3c86548a20d7bc2861aa4de044991a327bebad1a
• https://git.kernel.org/stable/c/810189546cb6c8f36443ed091d91f1f5d2fc2ec7
• https://git.kernel.org/stable/c/d3b504146c111548ab60b6ef7aad00bfb1db05a2
• https://git.kernel.org/stable/c/8b4a94b1510f6a46ec48494b52ee8f67eb4fc836
• https://git.kernel.org/stable/c/865ad8469fa24de1559f247d9426ab01e5ce3a56
• https://git.kernel.org/stable/c/a6b87bfc2ab5bccb7ad953693c85d9062aef3fdd