fsnotify_mmap_perm() requires a byte offset for the file about to be mmap'ed. But it is called from vm_mmap_pgoff(), which has a page offset. Previously the conversion was done incorrectly so let's fix it, being careful not to overflow on 32-bit platforms.
Discovered during code review.
Cc: stable@vger.kernel.org Fixes: 066e053fe208 ("fsnotify: add pre-content hooks on mmap()") Signed-off-by: Ryan Roberts ryan.roberts@arm.com --- Applies against today's mm-unstable (aa05a436eca8).
Thanks, Ryan
mm/util.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/util.c b/mm/util.c index 6c1d64ed0221..8989d5767528 100644 --- a/mm/util.c +++ b/mm/util.c @@ -566,6 +566,7 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flag, unsigned long pgoff) { + loff_t off = (loff_t)pgoff << PAGE_SHIFT; unsigned long ret; struct mm_struct *mm = current->mm; unsigned long populate; @@ -573,7 +574,7 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
ret = security_mmap_file(file, prot, flag); if (!ret) - ret = fsnotify_mmap_perm(file, prot, pgoff >> PAGE_SHIFT, len); + ret = fsnotify_mmap_perm(file, prot, off, len); if (!ret) { if (mmap_write_lock_killable(mm)) return -EINTR; -- 2.43.0