CVE-2024-58068: NULL Pointer Dereference

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

OPP: fix dev_pm_opp_find_bw_*() when bandwidth table not initialized

If a driver calls dev_pm_opp_find_bw_ceil/floor() the retrieve bandwidth from the OPP table but the bandwidth table was not created because the interconnect properties were missing in the OPP consumer node, the kernel will crash with:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 ... pc : _read_bw+0x8/0x10 lr : _opp_table_find_key+0x9c/0x174 ... Call trace: _read_bw+0x8/0x10 (P) _opp_table_find_key+0x9c/0x174 (L) _find_key+0x98/0x168 dev_pm_opp_find_bw_ceil+0x50/0x88 ...

In order to fix the crash, create an assert function to check if the bandwidth table was created before trying to get a bandwidth with _read_bw().