linux-kernel - Re: [PATCH v11 00/10] NTFS read-write driver GPL implementation by Paragon Software

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Date:   Fri, 30 Oct 2020 19:48:00 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Cc:     linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk,
        linux-kernel@...r.kernel.org, pali@...nel.org, dsterba@...e.cz,
        aaptel@...e.com, willy@...radead.org, rdunlap@...radead.org,
        joe@...ches.com, mark@...mstone.com, nborisov@...e.com,
        linux-ntfs-dev@...ts.sourceforge.net, anton@...era.com
Subject: Re: [PATCH v11 00/10] NTFS read-write driver GPL implementation by
 Paragon Software

On Fri, Oct 30, 2020 at 07:42:09PM -0700, Eric Biggers wrote:
> Hi Konstantin,
> 
> On Fri, Oct 30, 2020 at 06:02:29PM +0300, Konstantin Komarov wrote:
> > This patch adds NTFS Read-Write driver to fs/ntfs3.
> > 
> > Having decades of expertise in commercial file systems development and huge
> > test coverage, we at Paragon Software GmbH want to make our contribution to
> > the Open Source Community by providing implementation of NTFS Read-Write
> > driver for the Linux Kernel.
> > 
> > This is fully functional NTFS Read-Write driver. Current version works with
> > NTFS(including v3.1) and normal/compressed/sparse files and supports journal replaying.
> > 
> > We plan to support this version after the codebase once merged, and add new
> > features and fix bugs. For example, full journaling support over JBD will be
> > added in later updates.
> > 
> 
> Have you tried testing this filesystem using some of the kernel debugging
> options (lockdep, KASAN, etc.?).  I tried a basic test just for fun, and I
> immediately got a lockdep report:
> 
> mkfs.ntfs -f /dev/vdb
> mount /dev/vdb /mnt -t ntfs3
> echo foo > /mnt/foo
> 
> ======================================================
> WARNING: possible circular locking dependency detected
> 5.10.0-rc1-00275-ga34a2c322380 #33 Not tainted
> ------------------------------------------------------
> bash/160 is trying to acquire lock:
> ffff888011e68108 (&ni->ni_lock){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:959 [inline]
> ffff888011e68108 (&ni->ni_lock){+.+.}-{3:3}, at: ntfs_set_size+0xee/0x210 fs/ntfs3/inode.c:880
> 
> but task is already holding lock:
> ffff888011e68370 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_trylock include/linux/fs.h:794 [inline]
> ffff888011e68370 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: ntfs_file_write_iter+0x1bc/0x4e0 fs/ntfs3/file.c:1040
> 
> which lock already depends on the new lock.

Also trying to create a symlink causes a stack out-of-bounds access:

$ mkfs.ntfs -f /dev/vdb
$ mount /dev/vdb /mnt -t ntfs3
$ ln -s target /mnt/symlink

BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:399 [inline]
BUG: KASAN: stack-out-of-bounds in hdr_insert_de+0x224/0x4d0 fs/ntfs3/index.c:851
Read of size 32 at addr ffffc900007b7b10 by task ln/181

CPU: 1 PID: 181 Comm: ln Not tainted 5.10.0-rc1-00275-ga34a2c322380 #33
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.14.0-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa4/0xd9 lib/dump_stack.c:118
 print_address_description.constprop.0+0x1f/0x160 mm/kasan/report.c:385
 __kasan_report.cold+0x37/0x7f mm/kasan/report.c:545
 kasan_report+0x3e/0x60 mm/kasan/report.c:562
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0xfb/0x1d0 mm/kasan/generic.c:192
 memcpy+0x24/0x60 mm/kasan/common.c:105
 memcpy include/linux/string.h:399 [inline]
 hdr_insert_de+0x224/0x4d0 fs/ntfs3/index.c:851
 indx_insert_into_root+0x5d0/0x1d10 fs/ntfs3/index.c:1585
 indx_insert_entry+0x299/0x4e0 fs/ntfs3/index.c:1936
 ntfs_insert_reparse+0x133/0x1b0 fs/ntfs3/fsntfs.c:2425
 ntfs_create_inode+0x28ec/0x4590 fs/ntfs3/inode.c:1511
 ntfs_symlink+0xb1/0xf0 fs/ntfs3/namei.c:198
 vfs_symlink fs/namei.c:3960 [inline]
 vfs_symlink+0x237/0x380 fs/namei.c:3946
 do_symlinkat+0x125/0x220 fs/namei.c:3987
 __do_sys_symlinkat fs/namei.c:4001 [inline]
 __se_sys_symlinkat fs/namei.c:3998 [inline]
 __x64_sys_symlinkat+0x6e/0xb0 fs/namei.c:3998
 do_syscall_64+0x32/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fdaf2fb2b2b
Code: 73 01 c3 48 8b 0d 45 f3 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 0a 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 15 f3 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe428da378 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007ffe428da598 RCX: 00007fdaf2fb2b2b
RDX: 00007ffe428db812 RSI: 00000000ffffff9c RDI: 00007ffe428db80b
RBP: 00007ffe428da588 R08: 00000000ffffffff R09: 0000000000000000
R10: 00005647f9c2b340 R11: 0000000000000246 R12: 0000000000000002
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000


addr ffffc900007b7b10 is located in stack of task ln/181 at offset 32 in frame:
 ntfs_insert_reparse+0x0/0x1b0 fs/ntfs3/fsntfs.c:2387

this frame has 1 object:
 [32, 60) 're'

Memory state around the buggy address:
 ffffc900007b7a00: 00 00 00 00 00 f1 f1 f1 f1 f1 f1 04 f2 00 f3 f3
 ffffc900007b7a80: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
>ffffc900007b7b00: f1 f1 00 00 00 04 f3 f3 f3 f3 00 00 00 00 00 00
                                  ^
 ffffc900007b7b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900007b7c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
==================================================================