6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+004c1e0fced2b4bc3dcc@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 640d1930bef4 ("block: Add bio_for_each_folio_all()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240116212959.3413014-1-willy@xxxxxxxxxxxxx
[axboe: add unlikely() to error case]
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/bio.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -286,6 +286,11 @@ 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);
@@ -303,10 +308,8 @@ 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);
}
}
