CVE-2024-40901 scsi: mpt3sas: Avoid test/set_bit() operating in non-allocated memory

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

scsi: mpt3sas: Avoid test/set_bit() operating in non-allocated memory

There is a potential out-of-bounds access when using test_bit() on a single
word. The test_bit() and set_bit() functions operate on long values, and
when testing or setting a single word, they can exceed the word
boundary. KASAN detects this issue and produces a dump:

 BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0 (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29 drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas

 Write of size 8 at addr ffff8881d26e3c60 by task kworker/u1536:2/2965

For full log, please look at [1].

Make the allocation at least the size of sizeof(unsigned long) so that
set_bit() and test_bit() have sufficient room for read/write operations
without overwriting unallocated memory.

[1] Link: https://lore.kernel.org/all/[email protected]/