Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
hugetlbfs: check for pgoff value overflow
A vma with vm_pgoff large enough to overflow a loff_t type when converted to a byte offset can be passed via the remap_file_pages system call. The hugetlbfs mmap routine uses the byte offset to calculate reservations and file size. A sequence such as: mmap(0x20a00000, 0x600000, 0, 0x66033, -1, 0); remap_file_pages(0x20a00000, 0x600000, 0, 0x20000000000000, 0); will result in the following when task exits/file closed, kernel BUG at mm/hugetlb.c:749! Call Trace: hugetlbfs_evict_inode+0x2f/0x40 evict+0xcb/0x190 __dentry_kill+0xcb/0x150 __fput+0x164/0x1e0 task_work_run+0x84/0xa0 exit_to_usermode_loop+0x7d/0x80 do_syscall_64+0x18b/0x190 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 The overflowed pgoff value causes hugetlbfs to try to set up a mapping with a negative range (end < start) that leaves invalid state which causes the BUG. The previous overflow fix to this code was incomplete and did not take the remap_file_pages system call into account. [[email protected]: v3] Link: http://lkml.kernel.org/r/[email protected] [[email protected]: include mmdebug.h] [[email protected]: fix -ve left shift count on sh] Link: http://lkml.kernel.org/r/[email protected] Fixes: 045c7a3 ("hugetlbfs: fix offset overflow in hugetlbfs mmap") Signed-off-by: Mike Kravetz <[email protected]> Reported-by: Nic Losby <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: "Kirill A . Shutemov" <[email protected]> Cc: Yisheng Xie <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
- Loading branch information