In the Linux kernel, the following vulnerability has been resolved:
media: solo6x10: Check for out of bounds chip_id
Clang with CONFIG_UBSAN_SHIFT=y noticed a condition where a signed type
(literal "1" is an "int") could end up being shifted beyond 32 bits,
so instrumentation was added (and due to the double is_tw286x() call
seen via inlining), Clang decides the second one must now be undefined
behavior and elides the rest of the function[1]. This is a known problem
with Clang (that is still being worked on), but we can avoid the entire
problem by actually checking the existing max chip ID, and now there is
no runtime instrumentation added at all since everything is known to be
within bounds.
Additionally use an unsigned value for the shift to remove the
instrumentation even without the explicit bounds checking.
[hverkuil: fix checkpatch warning for is_tw286x]