6.1-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Wilcox (Oracle) willy@infradead.org
commit 7bed6f3d08b7af27b7015da8dc3acf2b9c1f21d7 upstream.
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: 640d1930bef4 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/bio.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -279,6 +279,11 @@ static inline void bio_first_folio(struc { struct bio_vec *bvec = bio_first_bvec_all(bio) + i;
+ if (unlikely(i >= bio->bi_vcnt)) { + fi->folio = NULL; + return; + } + fi->folio = page_folio(bvec->bv_page); fi->offset = bvec->bv_offset + PAGE_SIZE * (bvec->bv_page - &fi->folio->page); @@ -296,10 +301,8 @@ static inline void bio_next_folio(struct fi->offset = 0; fi->length = min(folio_size(fi->folio), fi->_seg_count); fi->_next = folio_next(fi->folio); - } else if (fi->_i + 1 < bio->bi_vcnt) { - bio_first_folio(fi, bio, fi->_i + 1); } else { - fi->folio = NULL; + bio_first_folio(fi, bio, fi->_i + 1); } }