From: Dmitry Vyukov <dvyukov@google.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: syzbot <syzbot+6a6bca8169ffda8ce77b@syzkaller.appspotmail.com>,
Borislav Petkov <bp@alien8.de>,
David Miller <davem@davemloft.net>,
Marco Elver <elver@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"H. Peter Anvin" <hpa@zytor.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Thomas Gleixner <tglx@linutronix.de>,
"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit
Date: Wed, 1 Apr 2020 09:04:10 +0200 [thread overview]
Message-ID: <CACT4Y+ZSTjPmPmiL_1JEdroNZXYgaKewDBEH6RugnhsDVd+bUQ@mail.gmail.com> (raw)
In-Reply-To: <20200331202706.GA127606@gmail.com>
On Tue, Mar 31, 2020 at 10:27 PM Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Tue, Mar 31, 2020 at 12:35:13PM -0700, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: b12d66a6 mm, kcsan: Instrument SLAB free with ASSERT_EXCLU..
> > git tree: https://github.com/google/ktsan.git kcsan
> > console output: https://syzkaller.appspot.com/x/log.txt?x=111f0865e00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=10bc0131c4924ba9
> > dashboard link: https://syzkaller.appspot.com/bug?extid=6a6bca8169ffda8ce77b
> > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+6a6bca8169ffda8ce77b@syzkaller.appspotmail.com
> >
> > ==================================================================
> > BUG: KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit
> >
> > write to 0xffff88809966e128 of 8 bytes by task 24119 on cpu 0:
> > u128_xor include/crypto/b128ops.h:67 [inline]
> > glue_cbc_decrypt_req_128bit+0x396/0x460 arch/x86/crypto/glue_helper.c:144
> > cbc_decrypt+0x26/0x40 arch/x86/crypto/serpent_avx2_glue.c:152
> > crypto_skcipher_decrypt+0x65/0x90 crypto/skcipher.c:652
> > _skcipher_recvmsg crypto/algif_skcipher.c:142 [inline]
> > skcipher_recvmsg+0x7fa/0x8c0 crypto/algif_skcipher.c:161
> > skcipher_recvmsg_nokey+0x5e/0x80 crypto/algif_skcipher.c:279
> > sock_recvmsg_nosec net/socket.c:886 [inline]
> > sock_recvmsg net/socket.c:904 [inline]
> > sock_recvmsg+0x92/0xb0 net/socket.c:900
> > ____sys_recvmsg+0x167/0x3a0 net/socket.c:2566
> > ___sys_recvmsg+0xb2/0x100 net/socket.c:2608
> > __sys_recvmsg+0x9d/0x160 net/socket.c:2642
> > __do_sys_recvmsg net/socket.c:2652 [inline]
> > __se_sys_recvmsg net/socket.c:2649 [inline]
> > __x64_sys_recvmsg+0x51/0x70 net/socket.c:2649
> > do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > read to 0xffff88809966e128 of 8 bytes by task 24118 on cpu 1:
> > u128_xor include/crypto/b128ops.h:67 [inline]
> > glue_cbc_decrypt_req_128bit+0x37c/0x460 arch/x86/crypto/glue_helper.c:144
> > cbc_decrypt+0x26/0x40 arch/x86/crypto/serpent_avx2_glue.c:152
> > crypto_skcipher_decrypt+0x65/0x90 crypto/skcipher.c:652
> > _skcipher_recvmsg crypto/algif_skcipher.c:142 [inline]
> > skcipher_recvmsg+0x7fa/0x8c0 crypto/algif_skcipher.c:161
> > skcipher_recvmsg_nokey+0x5e/0x80 crypto/algif_skcipher.c:279
> > sock_recvmsg_nosec net/socket.c:886 [inline]
> > sock_recvmsg net/socket.c:904 [inline]
> > sock_recvmsg+0x92/0xb0 net/socket.c:900
> > ____sys_recvmsg+0x167/0x3a0 net/socket.c:2566
> > ___sys_recvmsg+0xb2/0x100 net/socket.c:2608
> > __sys_recvmsg+0x9d/0x160 net/socket.c:2642
> > __do_sys_recvmsg net/socket.c:2652 [inline]
> > __se_sys_recvmsg net/socket.c:2649 [inline]
> > __x64_sys_recvmsg+0x51/0x70 net/socket.c:2649
> > do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > Reported by Kernel Concurrency Sanitizer on:
> > CPU: 1 PID: 24118 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > ==================================================================
> >
>
> I think this is a problem for almost all the crypto code. Due to AF_ALG, both
> the source and destination buffers can be userspace pages that were gotten with
> get_user_pages(). Such pages can be concurrently modified, not just by the
> kernel but also by userspace.
>
> I'm not sure what can be done about this.
Oh, I thought it's something more serious like a shared crypto object.
Thanks for debugging.
I think I've seen this before in another context (b/149818448):
BUG: KCSAN: data-race in copyin / copyin
write to 0xffff888103c8b000 of 4096 bytes by task 20917 on cpu 0:
instrument_copy_from_user include/linux/instrumented.h:106 [inline]
copyin+0xab/0xc0 lib/iov_iter.c:151
copy_page_from_iter_iovec lib/iov_iter.c:296 [inline]
copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942
process_vm_rw_pages mm/process_vm_access.c:46 [inline]
process_vm_rw_single_vec mm/process_vm_access.c:120 [inline]
process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218
process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
__do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
__se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
__x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9
write to 0xffff888103c8b000 of 4096 bytes by task 20918 on cpu 1:
instrument_copy_from_user include/linux/instrumented.h:106 [inline]
copyin+0xab/0xc0 lib/iov_iter.c:151
copy_page_from_iter_iovec lib/iov_iter.c:296 [inline]
copy_page_from_iter+0x23f/0x5f0 lib/iov_iter.c:942
process_vm_rw_pages mm/process_vm_access.c:46 [inline]
process_vm_rw_single_vec mm/process_vm_access.c:120 [inline]
process_vm_rw_core.isra.0+0x448/0x820 mm/process_vm_access.c:218
process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
__do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
__se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
__x64_sys_process_vm_writev+0x8b/0xb0 mm/process_vm_access.c:303
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Marco, I think we need to ignore all memory that comes from
get_user_pages() somehow. Either not set watchpoints at all, or
perhaps filter them out later if the check is not totally free.
next prev parent reply other threads:[~2020-04-01 7:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-31 19:35 KCSAN: data-race in glue_cbc_decrypt_req_128bit / glue_cbc_decrypt_req_128bit syzbot
2020-03-31 20:27 ` Eric Biggers
2020-04-01 7:04 ` Dmitry Vyukov [this message]
2020-04-01 10:24 ` Marco Elver
2020-04-01 16:20 ` Eric Biggers
2020-04-01 22:53 ` Herbert Xu
2020-04-14 17:49 ` Marco Elver
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CACT4Y+ZSTjPmPmiL_1JEdroNZXYgaKewDBEH6RugnhsDVd+bUQ@mail.gmail.com \
--to=dvyukov@google.com \
--cc=bp@alien8.de \
--cc=davem@davemloft.net \
--cc=ebiggers@kernel.org \
--cc=elver@google.com \
--cc=herbert@gondor.apana.org.au \
--cc=hpa@zytor.com \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=syzbot+6a6bca8169ffda8ce77b@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).