bcachefs: Don't allocate too-big bios

This fixes a null ptr deref in bio_alloc_bioset() -> biovec_slab()

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index 002fd35e6bfea65bcf86046e77e6cd79a6db83cd..ea2adcc213d08f577a565be2ff9fb8d697b2689e 100644 (file)
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -782,6 +782,8 @@ static struct bio *bch2_write_bio_alloc(struct bch_fs *c,
                                       ? ((unsigned long) buf & (PAGE_SIZE - 1))
                                       : 0), PAGE_SIZE);
 
+       pages = min(pages, BIO_MAX_VECS);
+
        bio = bio_alloc_bioset(NULL, pages, 0,
                               GFP_NOIO, &c->bio_write);
        wbio                    = wbio_init(bio);