In the Linux kernel, the following vulnerability has been resolved: crypto: ccp - Fix...

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

crypto: ccp - Fix snp_filter_reserved_mem_regions() off-by-one

Sashiko notes:

regarding the bounds check in snp_filter_reserved_mem_regions() called via walk_iomem_res_desc(): does the check if ((range_list->num_elements * 16 + 8) > PAGE_SIZE) allow an off-by-one heap buffer overflow?

If range_list->num_elements is 255, 255 * 16 + 8 = 4088, which is <= 4096. Writing range->base (8 bytes) fills 4088-4095, but writing range->page_count (4 bytes) would write to 4096-4099, overflowing the kzalloc-allocated PAGE_SIZE buffer.

Fix this by accounting for the entry about to be written to, in addition to the entries that are already allocated.