From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C2A6B29A1; Tue, 17 Feb 2026 20:52:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771361573; cv=none; b=Iv73Xv3sflYQT/wTGiaM98j4kT3wL+1mSy7E0qB81t6Xc6FpJ6SSLVPf9T7hTIRnLjLxDSD6J/zX4hA6MfoVFishx+ziMbTwYeOv4GpsExuPS0TzUNPzpe+8uTTeU7f/k6lQ6ZkV6l6WFW59DbLdTLa67O6CxZOxnQnOFYklk24= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771361573; c=relaxed/simple; bh=Iy5zuqIAiQjcpAfqBkLWFunVd3GXCGsgEGeq6f1PBJw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h2ptfoiKtBCMAJKIC6Sgaen/nxuVWmzYkHE9+2G/323DQaJGthHm2gpz4kvmfqEY0XHwOUUvbnwnyrZS4KrHDgr2NyK7JQuF6apBMyuicmAkx/oQLll0y0SCef6FKKb4n34jfquLnhKV922FobsF0JKDGnhHPUeUm5t/9s0abII= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sp/8QUu1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sp/8QUu1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3133DC4CEF7; Tue, 17 Feb 2026 20:52:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771361573; bh=Iy5zuqIAiQjcpAfqBkLWFunVd3GXCGsgEGeq6f1PBJw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sp/8QUu1+sC8rPmHchzgOyogk9pWs6VKBcs2OseS/kthtyWNYxxflXspSsORm4OHM IWexo1JTl3UO6aULGZ8mQTWYVgFo1U2QIgveu/aCd/HLR25bpM9oNJy/KmVGG937J1 COaBM6FqjSFVnOeji+iDv3uRQqygXFG3KmHde3XA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+9c4e33e12283d9437c25@syzkaller.appspotmail.com, Deepanshu Kartikey , Christian Brauner , Sasha Levin Subject: [PATCH 6.12 12/42] romfs: check sb_set_blocksize() return value Date: Tue, 17 Feb 2026 21:32:03 +0100 Message-ID: <20260217200006.476845755@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260217200005.998240758@linuxfoundation.org> References: <20260217200005.998240758@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Deepanshu Kartikey [ Upstream commit ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0 ] romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). Later, when sb_bread() attempts I/O with this oversized block size, it triggers a kernel BUG in folio_set_bh(): kernel BUG at fs/buffer.c:1582! BUG_ON(size > PAGE_SIZE); Fix by checking the return value of sb_set_blocksize() and failing the mount with -EINVAL if it returns 0. Reported-by: syzbot+9c4e33e12283d9437c25@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9c4e33e12283d9437c25 Signed-off-by: Deepanshu Kartikey Link: https://patch.msgid.link/20260113084037.1167887-1-kartikey406@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/romfs/super.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/romfs/super.c b/fs/romfs/super.c index 0addcc849ff2c..e83f9b78d7a16 100644 --- a/fs/romfs/super.c +++ b/fs/romfs/super.c @@ -458,7 +458,10 @@ static int romfs_fill_super(struct super_block *sb, struct fs_context *fc) #ifdef CONFIG_BLOCK if (!sb->s_mtd) { - sb_set_blocksize(sb, ROMBSIZE); + if (!sb_set_blocksize(sb, ROMBSIZE)) { + errorf(fc, "romfs: unable to set blocksize\n"); + return -EINVAL; + } } else { sb->s_blocksize = ROMBSIZE; sb->s_blocksize_bits = blksize_bits(ROMBSIZE); -- 2.51.0