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From: Aleksandr Nogikh <nogikh@google.com>
Date: Sat, 4 May 2024 11:58:37 +0200
Message-ID: <CANp29Y5_ho16ktzYM1jtXxwu2z5AFi4pt0ccGc2XPoz2aH+NMA@mail.gmail.com>
Subject: Re: [syzbot] [crypto?] KASAN: use-after-free Read in scatterwalk_copychunks
To: syzbot <syzbot+8c4acf719c3fc41e8439@syzkaller.appspotmail.com>, 
	Kent Overstreet <kent.overstreet@linux.dev>, linux-bcachefs@vger.kernel.org
Cc: davem@davemloft.net, herbert@gondor.apana.org.au, 
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, 
	syzkaller-bugs@googlegroups.com
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#syz set subsystems: bcachefs

On Sat, May 4, 2024 at 11:57=E2=80=AFAM syzbot
<syzbot+8c4acf719c3fc41e8439@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    9221b2819b8a Add linux-next specific files for 20240503
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=3D130f062f18000=
0
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3D8ab537f51a6a0=
d98
> dashboard link: https://syzkaller.appspot.com/bug?extid=3D8c4acf719c3fc41=
e8439
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Deb=
ian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=3D111abc97180=
000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=3D1005900498000=
0
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/3e67dbdc3c37/dis=
k-9221b281.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/ade618fa19f8/vmlinu=
x-9221b281.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/df12e5073c97/b=
zImage-9221b281.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/9035c2c411=
38/mount_0.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the comm=
it:
> Reported-by: syzbot+8c4acf719c3fc41e8439@syzkaller.appspotmail.com
>
> bcachefs (loop0): mounting version 1.7: mi_btree_bitmap opts=3Dmetadata_c=
hecksum=3Dnone,data_checksum=3Dnone,compression=3Dlz4,nojournal_transaction=
_names
> bcachefs (loop0): recovering from clean shutdown, journal seq 13
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> BUG: KASAN: use-after-free in memcpy_dir crypto/scatterwalk.c:23 [inline]
> BUG: KASAN: use-after-free in scatterwalk_copychunks+0x1cc/0x460 crypto/s=
catterwalk.c:38
> Read of size 32 at addr ffff888049380000 by task syz-executor169/5094
>
> CPU: 0 PID: 5094 Comm: syz-executor169 Not tainted 6.9.0-rc6-next-2024050=
3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G=
oogle 03/27/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  print_address_description mm/kasan/report.c:377 [inline]
>  print_report+0x169/0x550 mm/kasan/report.c:488
>  kasan_report+0x143/0x180 mm/kasan/report.c:601
>  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
>  __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
>  memcpy_dir crypto/scatterwalk.c:23 [inline]
>  scatterwalk_copychunks+0x1cc/0x460 crypto/scatterwalk.c:38
>  skcipher_next_slow+0x39d/0x480 crypto/skcipher.c:276
>  skcipher_walk_next+0x634/0xba0 crypto/skcipher.c:361
>  chacha_simd_stream_xor+0x67f/0xd10 arch/x86/crypto/chacha_glue.c:192
>  do_encrypt_sg fs/bcachefs/checksum.c:107 [inline]
>  do_encrypt+0x4de/0x7b0 fs/bcachefs/checksum.c:127
>  bset_encrypt fs/bcachefs/btree_io.h:120 [inline]
>  bch2_btree_node_read_done+0x1dca/0x5ed0 fs/bcachefs/btree_io.c:1090
>  btree_node_read_work+0x665/0x1300 fs/bcachefs/btree_io.c:1345
>  bch2_btree_node_read+0x2637/0x2c80 fs/bcachefs/btree_io.c:1730
>  __bch2_btree_root_read fs/bcachefs/btree_io.c:1769 [inline]
>  bch2_btree_root_read+0x61e/0x970 fs/bcachefs/btree_io.c:1793
>  read_btree_roots+0x22d/0x7b0 fs/bcachefs/recovery.c:472
>  bch2_fs_recovery+0x2334/0x36e0 fs/bcachefs/recovery.c:800
>  bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1030
>  bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2105
>  bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1917
>  legacy_get_tree+0xee/0x190 fs/fs_context.c:662
>  vfs_get_tree+0x90/0x2a0 fs/super.c:1780
>  do_new_mount+0x2be/0xb40 fs/namespace.c:3352
>  do_mount fs/namespace.c:3692 [inline]
>  __do_sys_mount fs/namespace.c:3898 [inline]
>  __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fa185da797a
> Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 8=
4 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff=
 ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffcd1a149e8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffcd1a14a00 RCX: 00007fa185da797a
> RDX: 000000002000f640 RSI: 000000002000f680 RDI: 00007ffcd1a14a00
> RBP: 0000000000000004 R08: 00007ffcd1a14a40 R09: 000000000000f62b
> R10: 0000000000010400 R11: 0000000000000282 R12: 0000000000010400
> R13: 00007ffcd1a14a40 R14: 0000000000000003 R15: 0000000001000000
>  </TASK>
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4938=
0
> flags: 0xfff00000000000(node=3D0|zone=3D1|lastcpupid=3D0x7ff)
> page_type: 0xffffff7f(buddy)
> raw: 00fff00000000000 ffffea0001249008 ffffea0001223008 0000000000000000
> raw: 0000000000000000 0000000000000006 00000000ffffff7f 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as freed
> page last allocated via order 0, migratetype Unmovable, gfp_mask 0x500cc2=
(GFP_HIGHUSER|__GFP_ACCOUNT), pid 4945, tgid 4945 (sshd), ts 47548197350, f=
ree_ts 47548625509
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
>  prep_new_page mm/page_alloc.c:1476 [inline]
>  get_page_from_freelist+0x2ce2/0x2d90 mm/page_alloc.c:3438
>  __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4696
>  alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
>  pipe_write+0x657/0x1a40 fs/pipe.c:513
>  new_sync_write fs/read_write.c:497 [inline]
>  vfs_write+0xa72/0xc90 fs/read_write.c:590
>  ksys_write+0x1a0/0x2c0 fs/read_write.c:643
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> page last free pid 4947 tgid 4947 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  free_pages_prepare mm/page_alloc.c:1088 [inline]
>  free_unref_page+0xd22/0xea0 mm/page_alloc.c:2601
>  __folio_put+0x3b9/0x620 mm/swap.c:129
>  pipe_buf_release include/linux/pipe_fs_i.h:219 [inline]
>  pipe_update_tail fs/pipe.c:224 [inline]
>  pipe_read+0x6f2/0x13e0 fs/pipe.c:344
>  new_sync_read fs/read_write.c:395 [inline]
>  vfs_read+0x9c4/0xbd0 fs/read_write.c:476
>  ksys_read+0x1a0/0x2c0 fs/read_write.c:619
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Memory state around the buggy address:
>  ffff88804937ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff88804937ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff888049380000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>                    ^
>  ffff888049380080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff888049380100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
>
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