From nobody Wed Apr 8 08:00:12 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EAFFC28D13 for ; Mon, 22 Aug 2022 09:41:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234132AbiHVJlx (ORCPT ); Mon, 22 Aug 2022 05:41:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234517AbiHVJlt (ORCPT ); Mon, 22 Aug 2022 05:41:49 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 959802FFF5; Mon, 22 Aug 2022 02:41:47 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 4910C1F8C6; Mon, 22 Aug 2022 09:41:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1661161306; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=M3r5c5Toc91HcVVVt7XVwoDf7zKZfsbphKJblBDQC9s=; b=Gsl58xvgTN1vEplfGhffVP0Cvn7KLT7D4zYtWQy643KISdCUGUZSgLlXYesnNRJymRwqVr Sv8iXTY9GWj+XYD6sgDZUxcbO1yS+2U1gVcEHNj4+XC6WnXVxz7nwJ4MBSxGw5+8CSn2df okNN0th1HSgMlqNv0Q8SBNzdnLON1mQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1661161306; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=M3r5c5Toc91HcVVVt7XVwoDf7zKZfsbphKJblBDQC9s=; b=ogpajHacZexQC89EVqMEhcQyZVb4PEWbmrEZAjgsCzYC3g0o4OGFQa5HO4TkTzXleh9w11 L8FQ9crjr5xwVjCQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id B460B13523; Mon, 22 Aug 2022 09:41:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id B1PeKFlPA2NSeAAAMHmgww (envelope-from ); Mon, 22 Aug 2022 09:41:45 +0000 Received: from localhost (brahms.olymp [local]) by brahms.olymp (OpenSMTPD) with ESMTPA id 5a23cab6; Mon, 22 Aug 2022 09:42:37 +0000 (UTC) From: =?UTF-8?q?Lu=C3=ADs=20Henriques?= To: Theodore Ts'o , Andreas Dilger Cc: wenqingliu0120@gmail.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?Lu=C3=ADs=20Henriques?= , Baokun Li Subject: [PATCH v4] ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0 Date: Mon, 22 Aug 2022 10:42:35 +0100 Message-Id: <20220822094235.2690-1-lhenriques@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When walking through an inode extents, the ext4_ext_binsearch_idx() function assumes that the extent header has been previously validated. However, the= re are no checks that verify that the number of entries (eh->eh_entries) is non-zero when depth is > 0. And this will lead to problems because the EXT_FIRST_INDEX() and EXT_LAST_INDEX() will return garbage and result in th= is: [ 135.245946] ------------[ cut here ]------------ [ 135.247579] kernel BUG at fs/ext4/extents.c:2258! [ 135.249045] invalid opcode: 0000 [#1] PREEMPT SMP [ 135.250320] CPU: 2 PID: 238 Comm: tmp118 Not tainted 5.19.0-rc8+ #4 [ 135.252067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS = rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 [ 135.255065] RIP: 0010:ext4_ext_map_blocks+0xc20/0xcb0 [ 135.256475] Code: [ 135.261433] RSP: 0018:ffffc900005939f8 EFLAGS: 00010246 [ 135.262847] RAX: 0000000000000024 RBX: ffffc90000593b70 RCX: 00000000000= 00023 [ 135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000003 RDI: ffff8880046= e922c [ 135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002c= a580c [ 135.268576] R10: 0000000000002602 R11: 0000000000000000 R12: 00000000000= 00024 [ 135.270477] R13: 0000000000000000 R14: 0000000000000024 R15: 00000000000= 00000 [ 135.272394] FS: 00007fdabdc56740(0000) GS:ffff88807dd00000(0000) knlGS:= 0000000000000000 [ 135.274510] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 135.276075] CR2: 00007ffc26bd4f00 CR3: 0000000006261004 CR4: 00000000001= 70ea0 [ 135.277952] Call Trace: [ 135.278635] [ 135.279247] ? preempt_count_add+0x6d/0xa0 [ 135.280358] ? percpu_counter_add_batch+0x55/0xb0 [ 135.281612] ? _raw_read_unlock+0x18/0x30 [ 135.282704] ext4_map_blocks+0x294/0x5a0 [ 135.283745] ? xa_load+0x6f/0xa0 [ 135.284562] ext4_mpage_readpages+0x3d6/0x770 [ 135.285646] read_pages+0x67/0x1d0 [ 135.286492] ? folio_add_lru+0x51/0x80 [ 135.287441] page_cache_ra_unbounded+0x124/0x170 [ 135.288510] filemap_get_pages+0x23d/0x5a0 [ 135.289457] ? path_openat+0xa72/0xdd0 [ 135.290332] filemap_read+0xbf/0x300 [ 135.291158] ? _raw_spin_lock_irqsave+0x17/0x40 [ 135.292192] new_sync_read+0x103/0x170 [ 135.293014] vfs_read+0x15d/0x180 [ 135.293745] ksys_read+0xa1/0xe0 [ 135.294461] do_syscall_64+0x3c/0x80 [ 135.295284] entry_SYSCALL_64_after_hwframe+0x46/0xb0 This patch simply adds an extra check in __ext4_ext_check(), verifying that eh_entries is not 0 when eh_depth is > 0. Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D215941 Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D216283 Cc: Baokun Li Signed-off-by: Lu=C3=ADs Henriques Reviewed-by: Jan Kara Reviewed-by:=C2=A0 Baokun Li --- fs/ext4/extents.c | 4 ++++ 1 file changed, 4 insertions(+) Changes since v3: - Fixed typo (I had 'eh_depth' instead of 'depth') Changes since v2: - Dropped usage of le16_to_cpu() because we're comparing values against 0 - Use 'depth' instead of 'eh->eh_depth' because we've checked earlier that both have the same value. diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index c148bb97b527..5235974126bd 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -460,6 +460,10 @@ static int __ext4_ext_check(const char *function, unsi= gned int line, error_msg =3D "invalid eh_entries"; goto corrupted; } + if (unlikely((eh->eh_entries =3D=3D 0) && (depth > 0))) { + error_msg =3D "eh_entries is 0 but eh_depth is > 0"; + goto corrupted; + } if (!ext4_valid_extent_entries(inode, eh, lblk, &pblk, depth)) { error_msg =3D "invalid extent entries"; goto corrupted;