From mboxrd@z Thu Jan 1 00:00:00 1970 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 2891AC6FA86 for ; Mon, 19 Sep 2022 15:12:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229607AbiISPMz (ORCPT ); Mon, 19 Sep 2022 11:12:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229811AbiISPMp (ORCPT ); Mon, 19 Sep 2022 11:12:45 -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 9797E2A736; Mon, 19 Sep 2022 08:12:42 -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 2E0B81F74A; Mon, 19 Sep 2022 15:12:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1663600361; 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: in-reply-to:in-reply-to:references:references; bh=HFF757gPeYM2C7iwVQjCQX1VV+JsPVPXoZQmvFMXoPc=; b=YuDcUARs/xkMfE6idEFhiU9LjYxFD3rS9rvFlCnOu4/CUePrpFbx5FJMtLdUpa7+Tt/ABj qxM2Bwb2rrTus+cxXMtCyFRxgxrm0RgP1VIp+Avmwh3jeuhHulMQ5dxkm8J6Sp29HKQDvm BY62Vx6CVYwGHcvbUSZYy95goOHyV4E= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1663600361; 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: in-reply-to:in-reply-to:references:references; bh=HFF757gPeYM2C7iwVQjCQX1VV+JsPVPXoZQmvFMXoPc=; b=VrV40lqbnBuzKMHQiQdJ+vkybcr7JjmXh2FVokCH4RGIahnL27/c/lcCre4lKAXxRQPWhe X/cEyqQAY0D7eDAw== 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 1E42B13A96; Mon, 19 Sep 2022 15:12:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id FvVEB+mGKGMXcwAAMHmgww (envelope-from ); Mon, 19 Sep 2022 15:12:41 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 9A63FA0682; Mon, 19 Sep 2022 17:12:40 +0200 (CEST) Date: Mon, 19 Sep 2022 17:12:40 +0200 From: Jan Kara To: =?utf-8?B?THXDrXM=?= Henriques Cc: Theodore Ts'o , Andreas Dilger , wenqingliu0120@gmail.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Baokun Li Subject: Re: [PATCH v4] ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0 Message-ID: <20220919151240.v3hoqppxi7rpombe@quack3> References: <20220822094235.2690-1-lhenriques@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220822094235.2690-1-lhenriques@suse.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 22-08-22 10:42:35, Luís Henriques wrote: > When walking through an inode extents, the ext4_ext_binsearch_idx() function > assumes that the extent header has been previously validated. However, there > 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 this: > > [ 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: 0000000000000023 > [ 135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000003 RDI: ffff8880046e922c > [ 135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002ca580c > [ 135.268576] R10: 0000000000002602 R11: 0000000000000000 R12: 0000000000000024 > [ 135.270477] R13: 0000000000000000 R14: 0000000000000024 R15: 0000000000000000 > [ 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: 0000000000170ea0 > [ 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=215941 > Link: https://bugzilla.kernel.org/show_bug.cgi?id=216283 > Cc: Baokun Li > Signed-off-by: Luís Henriques The patch looks good to me. Thanks for the fix. Feel free to add: Reviewed-by: Jan Kara Honza > 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, unsigned int line, > error_msg = "invalid eh_entries"; > goto corrupted; > } > + if (unlikely((eh->eh_entries == 0) && (depth > 0))) { > + error_msg = "eh_entries is 0 but eh_depth is > 0"; > + goto corrupted; > + } > if (!ext4_valid_extent_entries(inode, eh, lblk, &pblk, depth)) { > error_msg = "invalid extent entries"; > goto corrupted; -- Jan Kara SUSE Labs, CR