CVE-2024-38592

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

drm/mediatek: Init ddp_comp with devm_kcalloc()

In the case where conn_routes is true we allocate an extra slot in the ddp_comp array but mtkdrmcrtccreate() never seemed to initialize it in the test case I ran. For me, this caused a later crash when we looped through the array in mtkdrmcrtcmode_valid(). This showed up for me when I booted with slub_debug=FZPUA which poisons the memory initially. Without slub_debug I couldn't reproduce, presumably because the later code handles the value being NULL and in most cases (not guaranteed in all cases) the memory the allocator returned started out as 0.

It really doesn't hurt to initialize the array with devm_kcalloc() since the array is small and the overhead of initting a handful of elements to 0 is small. In general initting memory to zero is a safer practice and usually it's suggested to only use the non-initting alloc functions if you really need to.

Let's switch the function to use an allocation function that zeros the memory. For me, this avoids the crash.