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 0FB30C433FE for ; Thu, 10 Nov 2022 11:53:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230380AbiKJLxF (ORCPT ); Thu, 10 Nov 2022 06:53:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229528AbiKJLxC (ORCPT ); Thu, 10 Nov 2022 06:53:02 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B665D6CA20 for ; Thu, 10 Nov 2022 03:53:00 -0800 (PST) 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-out1.suse.de (Postfix) with ESMTPS id 5E09C22CC7; Thu, 10 Nov 2022 11:52:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1668081179; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m6jyYG8X7Y9H3uoDBRZJ6IFnZAFbqVKxt4W+XZRY/RU=; b=iALvoIHBsY407mBqOoj+xl1y71haO5aCcnuOTCnBFyh15I8wN6Z18t+PwBH3UXCej63tkk ptwP4+GLxevKj/qdTIKoXba1jLwgaWzjG4bobMR5xuN5eHoFCdA/3GqD/OTAgYGmH5NzDf Sirtm/AyKICpSH6E0FGLZV6mB2Me2hY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1668081179; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m6jyYG8X7Y9H3uoDBRZJ6IFnZAFbqVKxt4W+XZRY/RU=; b=isuVriHgHHO/ps/7qLQT1FS9LQ0P4Y1FpgsTbMXRQPdE4C5QhC+zcN1ej/ngi1NUskeqyG hJ29suqdCTpN02BQ== 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 4E1461332F; Thu, 10 Nov 2022 11:52:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Z0UFExvmbGMdQAAAMHmgww (envelope-from ); Thu, 10 Nov 2022 11:52:59 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id E03A1A0704; Thu, 10 Nov 2022 12:52:57 +0100 (CET) Date: Thu, 10 Nov 2022 12:52:57 +0100 From: Jan Kara To: Peng Zhang Cc: jack@suse.com, jack@suse.cz, yi.zhang@huawei.com, yujie.liu@intel.com, hch@lst.de, akpm@linux-foundation.org, bvanassche@acm.org, willy@infradead.org, linux-kernel@vger.kernel.org, syzbot+908340a8367281960537@syzkaller.appspotmail.com Subject: Re: [PATCH] udf: Fix a slab-out-of-bounds write bug in udf_write_aext() Message-ID: <20221110115257.itqilpn4x7npmzaa@quack3> References: <20221110014052.3039100-1-zhangpeng362@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221110014052.3039100-1-zhangpeng362@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! On Thu 10-11-22 01:40:52, Peng Zhang wrote: > From: ZhangPeng > > Syzbot reported a slab-out-of-bounds write bug: > > loop0: detected capacity change from 0 to 2048 > ================================================================== > BUG: KASAN: slab-out-of-bounds in udf_write_aext+0x8bc/0x8f0 > fs/udf/inode.c:2103 > Write of size 4 at addr ffff8880777c63f8 by task syz-executor216/3611 > > CPU: 0 PID: 3611 Comm: syz-executor216 Not tainted > 6.0.0-syzkaller-09589-g55be6084c8e0 #0 > Hardware name: Google Compute Engine/Google Compute Engine, BIOS > Google 09/22/2022 > Call Trace: > > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:317 [inline] > print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 > kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 > udf_write_aext+0x8bc/0x8f0 fs/udf/inode.c:2103 > udf_add_entry+0xd03/0x2ac0 fs/udf/namei.c:482 > udf_mkdir+0x145/0x650 fs/udf/namei.c:681 > vfs_mkdir+0x489/0x740 fs/namei.c:4013 > do_mkdirat+0x28c/0x310 fs/namei.c:4038 > __do_sys_mkdir fs/namei.c:4058 [inline] > __se_sys_mkdir fs/namei.c:4056 [inline] > __x64_sys_mkdir+0xf2/0x140 fs/namei.c:4056 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7fef3beda479 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 > f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 > f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffe952d4e28 EFLAGS: 00000246 ORIG_RAX: 0000000000000053 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fef3beda479 > RDX: 00007fef3be986e3 RSI: 0000000000000000 RDI: 0000000020000000 > RBP: 00007fef3be999b0 R08: 00007ffe952d4d10 R09: 0000000000000000 > R10: 00007ffe952d4cf0 R11: 0000000000000246 R12: 00007fef3be99a40 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > Allocated by task 3611: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > kasan_set_track mm/kasan/common.c:45 [inline] > set_alloc_info mm/kasan/common.c:437 [inline] > ____kasan_kmalloc mm/kasan/common.c:516 [inline] > ____kasan_kmalloc mm/kasan/common.c:475 [inline] > __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525 > kmalloc include/linux/slab.h:600 [inline] > kmalloc_array include/linux/slab.h:639 [inline] > kcalloc include/linux/slab.h:671 [inline] > udf_process_sequence+0xe9/0x4470 fs/udf/super.c:1689 > udf_load_sequence fs/udf/super.c:1813 [inline] > udf_check_anchor_block+0x44b/0x640 fs/udf/super.c:1852 > udf_scan_anchors+0x1b3/0x6d0 fs/udf/super.c:1885 > udf_find_anchor fs/udf/super.c:1941 [inline] > udf_load_vrs+0x27b/0xbe0 fs/udf/super.c:2006 > udf_fill_super+0x859/0x1a40 fs/udf/super.c:2184 > mount_bdev+0x34d/0x410 fs/super.c:1400 > legacy_get_tree+0x105/0x220 fs/fs_context.c:610 > vfs_get_tree+0x89/0x2f0 fs/super.c:1530 > do_new_mount fs/namespace.c:3040 [inline] > path_mount+0x1326/0x1e20 fs/namespace.c:3370 > do_mount fs/namespace.c:3383 [inline] > __do_sys_mount fs/namespace.c:3591 [inline] > __se_sys_mount fs/namespace.c:3568 [inline] > __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Freed by task 3611: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > ____kasan_slab_free mm/kasan/common.c:367 [inline] > ____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:329 > kasan_slab_free include/linux/kasan.h:200 [inline] > slab_free_hook mm/slub.c:1759 [inline] > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1785 > slab_free mm/slub.c:3539 [inline] > kfree+0xe2/0x580 mm/slub.c:4567 > udf_process_sequence+0x421/0x4470 fs/udf/super.c:1781 > udf_load_sequence fs/udf/super.c:1813 [inline] > udf_check_anchor_block+0x44b/0x640 fs/udf/super.c:1852 > udf_scan_anchors+0x1b3/0x6d0 fs/udf/super.c:1885 > udf_find_anchor fs/udf/super.c:1941 [inline] > udf_load_vrs+0x27b/0xbe0 fs/udf/super.c:2006 > udf_fill_super+0x859/0x1a40 fs/udf/super.c:2184 > mount_bdev+0x34d/0x410 fs/super.c:1400 > legacy_get_tree+0x105/0x220 fs/fs_context.c:610 > vfs_get_tree+0x89/0x2f0 fs/super.c:1530 > do_new_mount fs/namespace.c:3040 [inline] > path_mount+0x1326/0x1e20 fs/namespace.c:3370 > do_mount fs/namespace.c:3383 [inline] > __do_sys_mount fs/namespace.c:3591 [inline] > __se_sys_mount fs/namespace.c:3568 [inline] > __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > The buggy address belongs to the object at ffff8880777c6000 > which belongs to the cache kmalloc-512 of size 512 > The buggy address is located 504 bytes to the right of > 512-byte region [ffff8880777c6000, ffff8880777c6200) > > The buggy address belongs to the physical page: > page:ffffea0001ddf100 refcount:1 mapcount:0 mapping:0000000000000000 > index:0x0 pfn:0x777c4 > head:ffffea0001ddf100 order:2 compound_mapcount:0 compound_pincount:0 > flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) > raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888011841c80 > raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 2, migratetype Unmovable, gfp_mask > pid 2972, tgid 2972 (udevadm), ts 11705893480, free_ts 9906278250 > prep_new_page mm/page_alloc.c:2532 [inline] > get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283 > __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5549 > alloc_pages+0x1a6/0x270 mm/mempolicy.c:2270 > alloc_slab_page mm/slub.c:1829 [inline] > allocate_slab+0x27e/0x3d0 mm/slub.c:1974 > new_slab mm/slub.c:2034 [inline] > ___slab_alloc+0x84f/0xe80 mm/slub.c:3036 > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3123 > slab_alloc_node mm/slub.c:3214 [inline] > slab_alloc mm/slub.c:3256 [inline] > kmem_cache_alloc_trace+0x323/0x3e0 mm/slub.c:3287 > kmalloc include/linux/slab.h:600 [inline] > kzalloc include/linux/slab.h:733 [inline] > kernfs_fop_open+0x31a/0xec0 fs/kernfs/file.c:666 > do_dentry_open+0x6cc/0x13f0 fs/open.c:882 > do_open fs/namei.c:3557 [inline] > path_openat+0x1c92/0x28f0 fs/namei.c:3691 > do_filp_open+0x1b6/0x400 fs/namei.c:3718 > do_sys_openat2+0x16d/0x4c0 fs/open.c:1310 > do_sys_open fs/open.c:1326 [inline] > __do_sys_openat fs/open.c:1342 [inline] > __se_sys_openat fs/open.c:1337 [inline] > __x64_sys_openat+0x13f/0x1f0 fs/open.c:1337 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > page last free stack trace: > reset_page_owner include/linux/page_owner.h:24 [inline] > free_pages_prepare mm/page_alloc.c:1449 [inline] > free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1499 > free_unref_page_prepare mm/page_alloc.c:3380 [inline] > free_unref_page+0x19/0x4d0 mm/page_alloc.c:3476 > free_contig_range+0xb1/0x180 mm/page_alloc.c:9457 > destroy_args+0xa8/0x646 mm/debug_vm_pgtable.c:1031 > debug_vm_pgtable+0x2945/0x29d6 mm/debug_vm_pgtable.c:1354 > do_one_initcall+0xfe/0x650 init/main.c:1296 > do_initcall_level init/main.c:1369 [inline] > do_initcalls init/main.c:1385 [inline] > do_basic_setup init/main.c:1404 [inline] > kernel_init_freeable+0x6b1/0x73a init/main.c:1623 > kernel_init+0x1a/0x1d0 init/main.c:1512 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > Memory state around the buggy address: > ffff8880777c6280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8880777c6300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff8880777c6380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff8880777c6400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff8880777c6480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ================================================================== > > Writing to the address ptr will cause an out-of-bounds bug if the inode > allocation type is ICBTAG_FLAG_AD_SHORT (or ICBTAG_FLAG_AD_LONG), the > buffer head pointer is NULL, and iinfo->i_lenEAttr is 0. In this case, > the address ptr is iinfo->i_data - sizeof(struct short_ad), and the > out-of-bounds offset is the size of struct short_ad. This can be fixed > by adding the size of struct short_ad (or struct long_ad) to the address > ptr. > > Reported-by: syzbot+908340a8367281960537@syzkaller.appspotmail.com > Fixes: 2c948b3f86e5 ("udf: Avoid IO in udf_clear_inode") > Signed-off-by: ZhangPeng Thanks for the fix! So do I understand correctly that in this case the inode has type ICBTAG_FLAG_AD_SHORT and its size is 0 as well? Then I can see how what you describe is happening. But the fix is actually wrong, it will lead to writing extent to a wrong place in most cases. The problem rather is that in this particular case in udf_add_entry() epos.offset should not be decremented before calling udf_write_aext(). But when it should / should not be decremented is really messy. It needs a broader look and cleaning up... Honza > --- > fs/udf/inode.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/udf/inode.c b/fs/udf/inode.c > index 8d06daed549f..abb3257b4c74 100644 > --- a/fs/udf/inode.c > +++ b/fs/udf/inode.c > @@ -2090,10 +2090,15 @@ void udf_write_aext(struct inode *inode, struct extent_position *epos, > struct long_ad *lad; > struct udf_inode_info *iinfo = UDF_I(inode); > > - if (!epos->bh) > + if (!epos->bh) { > ptr = iinfo->i_data + epos->offset - > udf_file_entry_alloc_offset(inode) + > iinfo->i_lenEAttr; > + if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT) > + ptr = ptr + sizeof(struct short_ad); > + else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG) > + ptr = ptr + sizeof(struct long_ad); > + } > else > ptr = epos->bh->b_data + epos->offset; > > -- > 2.25.1 > -- Jan Kara SUSE Labs, CR