Please sign in to comment.
mtdchar: fix offset overflow detection
Sasha Levin has been running trinity in a KVM tools guest, and was able to trigger the BUG_ON() at arch/x86/mm/pat.c:279 (verifying the range of the memory type). The call trace showed that it was mtdchar_mmap() that created an invalid remap_pfn_range(). The problem is that mtdchar_mmap() does various really odd and subtle things with the vma page offset etc, and uses the wrong types (and the wrong overflow) detection for it. For example, the page offset may well be 32-bit on a 32-bit architecture, but after shifting it up by PAGE_SHIFT, we need to use a potentially 64-bit resource_size_t to correctly hold the full value. Also, we need to check that the vma length plus offset doesn't overflow before we check that it is smaller than the length of the mtdmap region. This fixes things up and tries to make the code a bit easier to read. Reported-and-tested-by: Sasha Levin <email@example.com> Acked-by: Suresh Siddha <firstname.lastname@example.org> Acked-by: Artem Bityutskiy <email@example.com> Cc: David Woodhouse <firstname.lastname@example.org> Cc: email@example.com Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
- Loading branch information...