From patchwork Tue Jan 16 21:29:59 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 13521279 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B230B2E653; Tue, 16 Jan 2024 21:30:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705440605; cv=none; b=Rs5U68eAR9Su9oiIJlgRjrqrz5Yu6Fmi4esyEIFQLSjQqlviPQSuZfD+E/2Smh6HHuwg0+9pEZ4h/yOSmpeVIY6vzC4ANqo7Ec3HYksn9Jrh6eXqClg0XaZ6b3Qh6g+Dpn+PuYl6vS77z7JNBI/2DCAlJRJ15Q080Ggd/HtiSmw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705440605; c=relaxed/simple; bh=IAWk1YprB3PG7VN0yzjiLV8oZKHAOS9ZB6C24VAJCCQ=; h=DKIM-Signature:Received:From:To:Cc:Subject:Date:Message-Id: X-Mailer:MIME-Version:Content-Transfer-Encoding; b=jQ/qJZTL0/ubzkNgugGhwxpe7oxG8zDwD1xlq7dmr4I3XVL9LL6LnYzGyCbVtNRatHfC7vsqOQv2WoHt8SZixOxaOHqydYKztegxTcyDmazO8C9DtWMeBrMlSjNOM2G/hJ+Qln/gqD3qSeP1ugqa4iPmgAMgrJATSG120Y45dlo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=jSf9328k; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jSf9328k" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:In-Reply-To:References; bh=HM/2mnrR5ku0dJRu3DvkRCaTPaWRj5EtYUk/YkITPe0=; b=jSf9328kIeMp0WquyPLyQD2UbG vdOiLmM3fVjvGvEIAGVSGmjkXI4q/ZzuI0kqep5Czy0xnrWg8fFBlWRV9bIzSn2IY/2ptCTijl0Ot 8fj9Prv++oNv4PoY1BL6q853A/5/e6Ohua7ySUW+rEIlKGOvNsKMz+wPz9JLSFFNnrkCIHYwxxSBg cbGME98WXP1OA3X/qfenOm1/VYdcD1xvi6zSl/0fq9MR7GkqBKRrloOGG8lJQKo8+yIKwDvFONzYc vRcYh6evnSqdD2J+aKAD4gACbN8iXbT0foOZsnHhVcDKt7YHNQYkvwvFLPZLzYUJm39YMdivO8T3E sqHQQ0jQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rPr0S-00EJsm-W2; Tue, 16 Jan 2024 21:30:01 +0000 From: "Matthew Wilcox (Oracle)" To: Jens Axboe Cc: "Matthew Wilcox (Oracle)" , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+8b23309d5788a79d3eea@syzkaller.appspotmail.com, syzbot+004c1e0fced2b4bc3dcc@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH] block: Fix iterating over an empty bio with bio_for_each_folio_all Date: Tue, 16 Jan 2024 21:29:59 +0000 Message-Id: <20240116212959.3413014-1-willy@infradead.org> X-Mailer: git-send-email 2.37.1 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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) --- include/linux/bio.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/include/linux/bio.h b/include/linux/bio.h index ec4db73e5f4e..1518f1201ddd 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -286,6 +286,11 @@ static inline void bio_first_folio(struct folio_iter *fi, struct bio *bio, { struct bio_vec *bvec = bio_first_bvec_all(bio) + i; + if (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 folio_iter *fi, struct bio *bio) 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); } }