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watch_queue: Fix to release page in ->release()

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commit c1853fbadc upstream.

When a pipe ring descriptor points to a notification message, the
refcount on the backing page is incremented by the generic get function,
but the release function, which marks the bitmap, doesn't drop the page
ref.

Fix this by calling generic_pipe_buf_release() at the end of
watch_queue_pipe_buf_release().

Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Howells 2022-03-11 13:23:46 +00:00 • committed by Greg Kroah-Hartman
commit 2039900aad
1 changed files with 1 additions and 0 deletions
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kernel/watch_queue.c
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@ -54,6 +54,7 @@ static void watch_queue_pipe_buf_release(struct pipe_inode_info *pipe,
bit += page->index;
set_bit(bit, wqueue->notes_bitmap);
generic_pipe_buf_release(pipe, buf);
}
// No try_steal function => no stealing