block: Fix iterating over an empty bio with bio_for_each_folio_all
If the bio contains no data, bio_first_folio() calls page_folio() on a NULL pointer and oopses. Move the test that we've reached the end of the bio from bio_next_folio() to bio_first_folio(). Reported-by: <syzbot+8b23309d5788a79d3eea@syzkaller.appspotmail.com> Reported-by: <syzbot+004c1e0fced2b4bc3dcc@syzkaller.appspotmail.com> Fixes: 640d1930 ("block: Add bio_for_each_folio_all()") Cc: stable@vger.kernel.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Link: https://lore.kernel.org/r/20240116212959.3413014-1-willy@infradead.org [axboe: add unlikely() to error case] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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