watch_queue: Fix the alloc bitmap size to reflect notes allocated

Currently, watch_queue_set_size() sets the number of notes available in wqueue->nr_notes according to the number of notes allocated, but sets the size of the bitmap to the unrounded number of notes originally asked for. Fix this by setting the bitmap size to the number of notes we're actually going to make available (ie. the number allocated). Fixes: c73be61 ("pipe: Add general notification queue support") Reported-by: Jann Horn <[email protected]> Signed-off-by: David Howells <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
wafgo · Mar 11, 2022 · 3b4c037 · 3b4c037
1 parent a66bd75
commit 3b4c037
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
@@ -243,6 +243,7 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes)
 		goto error;
 	}
 
+	nr_notes = nr_pages * WATCH_QUEUE_NOTES_PER_PAGE;
 	ret = pipe_resize_ring(pipe, roundup_pow_of_two(nr_notes));
 	if (ret < 0)
 		goto error;
@@ -266,7 +267,7 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes)
 	wqueue->notes = pages;
 	wqueue->notes_bitmap = bitmap;
 	wqueue->nr_pages = nr_pages;
-	wqueue->nr_notes = nr_pages * WATCH_QUEUE_NOTES_PER_PAGE;
+	wqueue->nr_notes = nr_notes;
 	return 0;
 
 error_p: