From: Kent Overstreet <kent.overstreet@gmail.com>
Date: Wed, 13 Oct 2021 17:45:46 +0000 (-0400)
Subject: bcachefs: Don't allocate too-big bios
X-Git-Tag: v6.7-rc1~201^2~1358
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=edeb986b017e9489add4daa7e61bc79cdbfb913c;p=thirdparty%2Fkernel%2Flinux.git

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 002fd35e6bfea..ea2adcc213d08 100644
--- 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);