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fsnotify: pass correct offset to fsnotify_mmap_perm()

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commit 28bba2c2935e219d6cb6946e16b9a0b7c47913be upstream.

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.

Link: https://lkml.kernel.org/r/20251003155238.2147410-1-ryan.roberts@arm.com
Fixes: 066e053fe2 ("fsnotify: add pre-content hooks on mmap()")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Kiryl Shutsemau <kas@kernel.org>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ryan Roberts
2025-10-03 16:52:36 +01:00
committed by Greg Kroah-Hartman
parent 8a09a62f0c
commit 553bc7d462
1 changed files with 2 additions and 1 deletions
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3
mm/util.c
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@@ -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;