In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Fix NPD issue on partial unmap of an evicted BO This commit fixes t...

In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Fix NPD issue on partial unmap of an evicted BO This commit fixes the NULL pointer dereference issue that would have happened on the split of GPU mapping due to partial unmap of an evicted BO. There is a logic to handle the partial unmap of huge pages when the GPU mapping is split. That logic was not being completely skipped for the VMA of an evicted BO and that resulted in a NPD possibility for the 'bo->backing.pages' pointer, which is set to NULL when pages of a BO are released on eviction. Following dump was seen when a partial unmap was exercised for an evicted BO. Unable to handle kernel paging request at virtual address 0000000000002000 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000008842e8000 [0000000000002000] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000004 [#1] SMP pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : iova_mapped_as_huge_page+0x20/0x68 [panthor] lr : panthor_gpuva_sm_step_remap+0x39c/0x498 [panthor] sp : ffff800086193920 x29: ffff800086193920 x28: ffff800086193a18 x27: ffff800086193b80 x26: 000000000040000…