In the Linux kernel, the following vulnerability has been resolved: ext2/dax: Fix ext2_setsize when len is page aligned PAGE_ALIGN(x) macro gives the next highest value which is multiple of pagesize. But if x is already page aligned then it simply returns x. So, if x passed is 0 in dax_zero_range() function, that means the length gets passed as 0 to ->iomap_begin(). In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on here in ext2_get_blocks(). BUG_ON(maxblocks == 0); Instead we should be calling dax_truncate_page() here which takes care of it. i.e. it only calls dax_zero_range if the offset is not page/block aligned. This can be easily triggered with following on fsdax mounted pmem device. dd if=/dev/zero of=file count=1 bs=512 truncate -s 0 file [79.525838] EX