On Wed, Nov 22, 2017 at 02:58:59PM +0100, Jann Horn wrote:
commit 373c4557d2aa362702c4c2d41288fb1e54990b7c upstream.
This matters at least for the mincore syscall, which will otherwise copy uninitialized memory from the page allocator to userspace. It is probably also a correctness error for /proc/$pid/pagemap, but I haven't tested that.
Removing the `walk->hugetlb_entry` condition in walk_hugetlb_range() has no effect because the caller already checks for that.
This only reports holes in hugetlb ranges to callers who have specified a hugetlb_entry callback.
This issue was found using an AFL-based fuzzer.
v2:
- don't crash on ->pte_hole==NULL (Andrew Morton)
- add Cc stable (Andrew Morton)
Changed for 4.4/4.9 stable backport:
- fix up conflict in the huge_pte_offset() call
Fixes: 1e25a271c8ac ("mincore: apply page table walker on do_mincore()") Signed-off-by: Jann Horn jannh@google.com
Please apply this patch to <=4.9 stable trees instead of the original patch.
Thanks for the backport!
greg k-h