* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 2:42 ` syzbot
0 siblings, 0 replies; 30+ messages in thread
From: syzbot @ 2019-10-17 2:42 UTC (permalink / raw)
To: aou, dhowells, jarkko.sakkinen, jmorris, keyrings, linux-kernel,
linux-riscv, linux-security-module, palmer, serge,
syzkaller-bugs, torvalds
syzbot has bisected this bug to:
commit 0570bc8b7c9b41deba6f61ac218922e7168ad648
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Jul 18 19:26:59 2019 +0000
Merge tag 'riscv/for-v5.3-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11b6e2bb600000
start commit: bc88f85c kthread: make __kthread_queue_delayed_work static
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=13b6e2bb600000
console output: https://syzkaller.appspot.com/x/log.txt?x=15b6e2bb600000
kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
dashboard link: https://syzkaller.appspot.com/bug?extid=6455648abc28dbdd1e7f
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c8adab600000
Reported-by: syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com
Fixes: 0570bc8b7c9b ("Merge tag 'riscv/for-v5.3-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 2:42 ` syzbot
0 siblings, 0 replies; 30+ messages in thread
From: syzbot @ 2019-10-17 2:42 UTC (permalink / raw)
To: aou, dhowells, jarkko.sakkinen, jmorris, keyrings, linux-kernel,
linux-riscv, linux-security-module, palmer, serge,
syzkaller-bugs, torvalds
syzbot has bisected this bug to:
commit 0570bc8b7c9b41deba6f61ac218922e7168ad648
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Jul 18 19:26:59 2019 +0000
Merge tag 'riscv/for-v5.3-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11b6e2bb600000
start commit: bc88f85c kthread: make __kthread_queue_delayed_work static
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=13b6e2bb600000
console output: https://syzkaller.appspot.com/x/log.txt?x=15b6e2bb600000
kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
dashboard link: https://syzkaller.appspot.com/bug?extid=6455648abc28dbdd1e7f
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c8adab600000
Reported-by: syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com
Fixes: 0570bc8b7c9b ("Merge tag 'riscv/for-v5.3-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 2:42 ` syzbot
(?)
@ 2019-10-17 15:53 ` Linus Torvalds
-1 siblings, 0 replies; 30+ messages in thread
From: Linus Torvalds @ 2019-10-17 15:53 UTC (permalink / raw)
To: syzbot
Cc: aou, Palmer Dabbelt, syzkaller-bugs, James Morris James Morris,
Jarkko Sakkinen, Linux Kernel Mailing List, David Howells,
LSM List, keyrings, linux-riscv, Serge E. Hallyn
On Wed, Oct 16, 2019 at 7:42 PM syzbot
<syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
>
> syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> 'riscv/for-v5.3-rc1' ...")
Yeah, that looks unlikely. The only non-riscv changes are from
documentation updates and moving a config variable around.
Looks like the crash is quite unlikely, and only happens in one out of
ten runs for the ones it has happened to.
The backtrace looks simple enough, though:
RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
__key_get include/linux/key.h:281 [inline]
find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
__do_sys_add_key security/keys/keyctl.c:132 [inline]
__se_sys_add_key security/keys/keyctl.c:72 [inline]
__x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
which to me implies that there's some locking bug, and somebody
released the key without holding a lock.
That code looks a bit confused to me. Releasing a key without holding
a lock looks permitted, but if that's the case then __key_get() is
complete garbage. It would need to use 'refcount_inc_not_zero()' and
failure would require failing the caller.
But I haven't followed the key locking rules, so who knows. That "put
without lock" scenario would explain the crash, though.
David?
Linus
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 15:53 ` Linus Torvalds
0 siblings, 0 replies; 30+ messages in thread
From: Linus Torvalds @ 2019-10-17 15:53 UTC (permalink / raw)
To: syzbot
Cc: aou, Palmer Dabbelt, syzkaller-bugs, James Morris James Morris,
Jarkko Sakkinen, Linux Kernel Mailing List, David Howells,
LSM List, keyrings, linux-riscv, Serge E. Hallyn
On Wed, Oct 16, 2019 at 7:42 PM syzbot
<syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
>
> syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> 'riscv/for-v5.3-rc1' ...")
Yeah, that looks unlikely. The only non-riscv changes are from
documentation updates and moving a config variable around.
Looks like the crash is quite unlikely, and only happens in one out of
ten runs for the ones it has happened to.
The backtrace looks simple enough, though:
RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
__key_get include/linux/key.h:281 [inline]
find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
__do_sys_add_key security/keys/keyctl.c:132 [inline]
__se_sys_add_key security/keys/keyctl.c:72 [inline]
__x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
which to me implies that there's some locking bug, and somebody
released the key without holding a lock.
That code looks a bit confused to me. Releasing a key without holding
a lock looks permitted, but if that's the case then __key_get() is
complete garbage. It would need to use 'refcount_inc_not_zero()' and
failure would require failing the caller.
But I haven't followed the key locking rules, so who knows. That "put
without lock" scenario would explain the crash, though.
David?
Linus
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 15:53 ` Linus Torvalds
0 siblings, 0 replies; 30+ messages in thread
From: Linus Torvalds @ 2019-10-17 15:53 UTC (permalink / raw)
To: syzbot
Cc: aou, David Howells, Jarkko Sakkinen, James Morris James Morris,
keyrings, Linux Kernel Mailing List, linux-riscv, LSM List,
Palmer Dabbelt, Serge E. Hallyn, syzkaller-bugs
On Wed, Oct 16, 2019 at 7:42 PM syzbot
<syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
>
> syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> 'riscv/for-v5.3-rc1' ...")
Yeah, that looks unlikely. The only non-riscv changes are from
documentation updates and moving a config variable around.
Looks like the crash is quite unlikely, and only happens in one out of
ten runs for the ones it has happened to.
The backtrace looks simple enough, though:
RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
__key_get include/linux/key.h:281 [inline]
find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
__do_sys_add_key security/keys/keyctl.c:132 [inline]
__se_sys_add_key security/keys/keyctl.c:72 [inline]
__x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
which to me implies that there's some locking bug, and somebody
released the key without holding a lock.
That code looks a bit confused to me. Releasing a key without holding
a lock looks permitted, but if that's the case then __key_get() is
complete garbage. It would need to use 'refcount_inc_not_zero()' and
failure would require failing the caller.
But I haven't followed the key locking rules, so who knows. That "put
without lock" scenario would explain the crash, though.
David?
Linus
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 15:53 ` Linus Torvalds
(?)
@ 2019-10-17 16:00 ` Eric Biggers
-1 siblings, 0 replies; 30+ messages in thread
From: Eric Biggers @ 2019-10-17 16:00 UTC (permalink / raw)
To: Linus Torvalds
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, David Howells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="maccentraleurope", Size: 2662 bytes --]
On Thu, Oct 17, 2019 at 08:53:06AM -0700, Linus Torvalds wrote:
> On Wed, Oct 16, 2019 at 7:42 PM syzbot
> <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
>
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
>
> David?
>
Yes this is a bogus bisection.
The key is supposed to have refcount >= 1 since it's in a keyring.
So some bug is causing it to have refcount 0. Perhaps some place calling
key_put() too many times.
Unfortunately I can't get the reproducer to work locally.
Note that there are 2 other syzbot reports that look related.
No reproducers for them, though:
Title: KASAN: use-after-free Read in key_put
Last occurred: 1 day ago
Reported: 28 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?idñ3750b1124e01191250cf930086dcc40740fa30
Original thread: https://lore.kernel.org/lkml/0000000000008c3e590592cf4b7f@google.com/T/#u
Title: KASAN: use-after-free Read in keyring_compare_object
Last occurred: 49 days ago
Reported: 84 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?idR9ab6a98286c2a97c445988a62760a58d4a1d4b
Original thread: https://lore.kernel.org/lkml/000000000000038ef6058e6f3592@google.com/T/#u
- Eric
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 16:00 ` Eric Biggers
0 siblings, 0 replies; 30+ messages in thread
From: Eric Biggers @ 2019-10-17 16:00 UTC (permalink / raw)
To: Linus Torvalds
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, David Howells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
On Thu, Oct 17, 2019 at 08:53:06AM -0700, Linus Torvalds wrote:
> On Wed, Oct 16, 2019 at 7:42 PM syzbot
> <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
>
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
>
> David?
>
Yes this is a bogus bisection.
The key is supposed to have refcount >= 1 since it's in a keyring.
So some bug is causing it to have refcount 0. Perhaps some place calling
key_put() too many times.
Unfortunately I can't get the reproducer to work locally.
Note that there are 2 other syzbot reports that look related.
No reproducers for them, though:
Title: KASAN: use-after-free Read in key_put
Last occurred: 1 day ago
Reported: 28 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?id=f13750b1124e01191250cf930086dcc40740fa30
Original thread: https://lore.kernel.org/lkml/0000000000008c3e590592cf4b7f@google.com/T/#u
Title: KASAN: use-after-free Read in keyring_compare_object
Last occurred: 49 days ago
Reported: 84 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?id=529ab6a98286c2a97c445988a62760a58d4a1d4b
Original thread: https://lore.kernel.org/lkml/000000000000038ef6058e6f3592@google.com/T/#u
- Eric
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-17 16:00 ` Eric Biggers
0 siblings, 0 replies; 30+ messages in thread
From: Eric Biggers @ 2019-10-17 16:00 UTC (permalink / raw)
To: Linus Torvalds
Cc: syzbot, aou, David Howells, Jarkko Sakkinen,
James Morris James Morris, keyrings, Linux Kernel Mailing List,
linux-riscv, LSM List, Palmer Dabbelt, Serge E. Hallyn,
syzkaller-bugs
On Thu, Oct 17, 2019 at 08:53:06AM -0700, Linus Torvalds wrote:
> On Wed, Oct 16, 2019 at 7:42 PM syzbot
> <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
>
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
>
> David?
>
Yes this is a bogus bisection.
The key is supposed to have refcount >= 1 since it's in a keyring.
So some bug is causing it to have refcount 0. Perhaps some place calling
key_put() too many times.
Unfortunately I can't get the reproducer to work locally.
Note that there are 2 other syzbot reports that look related.
No reproducers for them, though:
Title: KASAN: use-after-free Read in key_put
Last occurred: 1 day ago
Reported: 28 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?id=f13750b1124e01191250cf930086dcc40740fa30
Original thread: https://lore.kernel.org/lkml/0000000000008c3e590592cf4b7f@google.com/T/#u
Title: KASAN: use-after-free Read in keyring_compare_object
Last occurred: 49 days ago
Reported: 84 days ago
Branches: Mainline
Dashboard link: https://syzkaller.appspot.com/bug?id=529ab6a98286c2a97c445988a62760a58d4a1d4b
Original thread: https://lore.kernel.org/lkml/000000000000038ef6058e6f3592@google.com/T/#u
- Eric
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 16:00 ` Eric Biggers
@ 2019-10-18 10:54 ` Tetsuo Handa
-1 siblings, 0 replies; 30+ messages in thread
From: Tetsuo Handa @ 2019-10-18 10:54 UTC (permalink / raw)
To: Eric Biggers; +Cc: Linus Torvalds, syzbot, keyrings, LSM List, syzkaller-bugs
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="maccentraleurope", Size: 1338 bytes --]
On 2019/10/18 1:00, Eric Biggers wrote:
> The key is supposed to have refcount >= 1 since it's in a keyring.
> So some bug is causing it to have refcount 0. Perhaps some place calling
> key_put() too many times.
>
> Unfortunately I can't get the reproducer to work locally.
>
> Note that there are 2 other syzbot reports that look related.
> No reproducers for them, though:
>
> Title: KASAN: use-after-free Read in key_put
> Last occurred: 1 day ago
> Reported: 28 days ago
> Branches: Mainline
> Dashboard link: https://syzkaller.appspot.com/bug?idñ3750b1124e01191250cf930086dcc40740fa30
> Original thread: https://lore.kernel.org/lkml/0000000000008c3e590592cf4b7f@google.com/T/#u
>
> Title: KASAN: use-after-free Read in keyring_compare_object
> Last occurred: 49 days ago
> Reported: 84 days ago
> Branches: Mainline
> Dashboard link: https://syzkaller.appspot.com/bug?idR9ab6a98286c2a97c445988a62760a58d4a1d4b
> Original thread: https://lore.kernel.org/lkml/000000000000038ef6058e6f3592@google.com/T/#u
>
I don't know about keys, but I rather suspect lack of serialization locks between
"looking up for checking existing keys" versus "looking up for garbage collection".
Can we dump locks held by current thread when panic() is called?
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 16:00 ` Eric Biggers
@ 2019-10-18 16:45 ` David Howells
-1 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-18 16:45 UTC (permalink / raw)
To: Tetsuo Handa
Cc: dhowells, Eric Biggers, Linus Torvalds, syzbot, keyrings,
LSM List, syzkaller-bugs
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> I don't know about keys, but I rather suspect lack of serialization locks
> between "looking up for checking existing keys" versus "looking up for
> garbage collection".
The garbage collector holds key_serial_lock when walking key_serial_tree
looking for keys to destroy.
As the gc is the *only* thing that is permitted to remove a key from
key_serial_tree, it can safely keep a cursor pointer to the node it was
looking at when it drops the lock - and then resume scanning once it has taken
the lock again.
When find_key_to_update() is looking for a key that might be updated, the
caller *must* be holding the destination keyring lock and every key in the
keyring should have at least one ref on it held by the keyring - so none of
them should get destroyed by the garbage collector.
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-18 16:45 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-18 16:45 UTC (permalink / raw)
To: Tetsuo Handa
Cc: dhowells, Eric Biggers, Linus Torvalds, syzbot, keyrings,
LSM List, syzkaller-bugs
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> I don't know about keys, but I rather suspect lack of serialization locks
> between "looking up for checking existing keys" versus "looking up for
> garbage collection".
The garbage collector holds key_serial_lock when walking key_serial_tree
looking for keys to destroy.
As the gc is the *only* thing that is permitted to remove a key from
key_serial_tree, it can safely keep a cursor pointer to the node it was
looking at when it drops the lock - and then resume scanning once it has taken
the lock again.
When find_key_to_update() is looking for a key that might be updated, the
caller *must* be holding the destination keyring lock and every key in the
keyring should have at least one ref on it held by the keyring - so none of
them should get destroyed by the garbage collector.
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 2:42 ` syzbot
(?)
@ 2019-10-18 16:38 ` David Howells
-1 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-18 16:38 UTC (permalink / raw)
To: Linus Torvalds
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
find_key_to_update() must be called with the keyring-to-be-searched locked, as
stated in the comment on that function.
If a key-to-be-updated can be found in that keyring, then the keyring must be
holding a ref on that key already, so it's refcount must be > 0, so it
shouldn't be necessary to use refcount_inc_not_zero().
There shouldn't be a race with key_link(), key_unlink(), key_move(),
keyring_clear() or keyring_gc() (garbage collection) as all of those take a
write-lock on the keyring.
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
That shouldn't explain it. When key_put() reduces the refcount to 0, it just
schedules the garbage collector. It doesn't touch the key again directly.
I would guess that something incorrectly put a ref when it shouldn't have. Do
we know which type of key is involved? Looking at the syzkaller reproducer,
it's adding an encrypted key and a user key to the process keyring -
presumably repeating the procedure within the same process, hence how it finds
something to update.
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-18 16:38 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-18 16:38 UTC (permalink / raw)
To: Linus Torvalds
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
find_key_to_update() must be called with the keyring-to-be-searched locked, as
stated in the comment on that function.
If a key-to-be-updated can be found in that keyring, then the keyring must be
holding a ref on that key already, so it's refcount must be > 0, so it
shouldn't be necessary to use refcount_inc_not_zero().
There shouldn't be a race with key_link(), key_unlink(), key_move(),
keyring_clear() or keyring_gc() (garbage collection) as all of those take a
write-lock on the keyring.
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
That shouldn't explain it. When key_put() reduces the refcount to 0, it just
schedules the garbage collector. It doesn't touch the key again directly.
I would guess that something incorrectly put a ref when it shouldn't have. Do
we know which type of key is involved? Looking at the syzkaller reproducer,
it's adding an encrypted key and a user key to the process keyring -
presumably repeating the procedure within the same process, hence how it finds
something to update.
David
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-18 16:38 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-18 16:38 UTC (permalink / raw)
To: Linus Torvalds
Cc: dhowells, syzbot, aou, Jarkko Sakkinen,
James Morris James Morris, keyrings, Linux Kernel Mailing List,
linux-riscv, LSM List, Palmer Dabbelt, Serge E. Hallyn,
syzkaller-bugs
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
>
> That code looks a bit confused to me. Releasing a key without holding
> a lock looks permitted, but if that's the case then __key_get() is
> complete garbage. It would need to use 'refcount_inc_not_zero()' and
> failure would require failing the caller.
find_key_to_update() must be called with the keyring-to-be-searched locked, as
stated in the comment on that function.
If a key-to-be-updated can be found in that keyring, then the keyring must be
holding a ref on that key already, so it's refcount must be > 0, so it
shouldn't be necessary to use refcount_inc_not_zero().
There shouldn't be a race with key_link(), key_unlink(), key_move(),
keyring_clear() or keyring_gc() (garbage collection) as all of those take a
write-lock on the keyring.
> But I haven't followed the key locking rules, so who knows. That "put
> without lock" scenario would explain the crash, though.
That shouldn't explain it. When key_put() reduces the refcount to 0, it just
schedules the garbage collector. It doesn't touch the key again directly.
I would guess that something incorrectly put a ref when it shouldn't have. Do
we know which type of key is involved? Looking at the syzkaller reproducer,
it's adding an encrypted key and a user key to the process keyring -
presumably repeating the procedure within the same process, hence how it finds
something to update.
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 2:42 ` syzbot
(?)
@ 2019-10-22 10:35 ` David Howells
-1 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 10:35 UTC (permalink / raw)
To: Linus Torvalds, Mimi Zohar
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
I'm wondering if this is actually a bug in the error handling in the encrypted
key type. Looking in the syzbot console log, there's a lot of output from
there prior to the crash, of which the following is an excerpt:
[ 248.516746][T27381] encrypted_key: key user:syz not found
[ 248.524392][T27382] encrypted_key: key user:syz not found
[ 248.616141][T27392] encrypted_key: key user:syz not found
[ 248.618890][T27393] encrypted_key: key user:syz not found
[ 248.690844][T27404] encrypted_key: key user:syz not found
[ 248.739405][T27403] encrypted_key: key user:syz not found
[ 248.804881][T27417] encrypted_key: key user:syz not found
[ 248.828354][T27418] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.925249][T27427] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.928200][T27415] Bad refcount user syz
[ 248.934043][T27428] encrypted_key: key user:syz not found
[ 248.939502][T27429] encrypted_key: key user:syz not found
[ 248.968744][T27434] encrypted_key: key user:syz not found
[ 248.982201][T27415] ==================================================================
[ 248.996072][T27415] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x81/0x200
Note that the "Bad refcount user syz" is a bit I patched in to print the type
and description of the key that incurred the error.
It's a tad difficult to say exactly what's going on since I've no idea what
the syzbot reproducer is actually doing.
#{"threaded":true,"collide":true,"repeat":true,"procs":6,"sandbox":"namespace","fault_call":-1,"tun":true,"netdev":true,"resetnet":true,"cgroups":true,"binfmt_misc":true,"close_fds":true,"tmpdir":true,"segv":true}
perf_event_open(&(0x7f000001d000)={0x1, 0x70, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0x0)
keyctl$instantiate(0xc, 0x0, &(0x7f0000000100)=ANY=[@ANYBLOB='new default user:syz 04096'], 0x1, 0x0)
r0 = add_key(&(0x7f0000000140)='encrypted\x00', &(0x7f0000000180)={'syz'}, &(0x7f0000000100), 0xca, 0xfffffffffffffffe)
add_key$user(&(0x7f0000000040)='user\x00', &(0x7f0000000000)={'syz'}, &(0x7f0000000440)='X', 0x1, 0xfffffffffffffffe)
keyctl$read(0xb, r0, &(0x7f0000000240)=""/112, 0x349b7f55)
However, it looks like the encrypted key type is trying to access a user key,
so maybe there's an overput there? I'm trying to insert more debugging, but
the test doesn't always fail.
syzbot <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> HEAD commit: bc88f85c kthread: make __kthread_queue_delayed_work static
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1730584b600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
> dashboard link: https://syzkaller.appspot.com/bug?extid=6455648abc28dbdd1e7f
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c8adab600000
David
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-22 10:35 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 10:35 UTC (permalink / raw)
To: Linus Torvalds, Mimi Zohar
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Serge E. Hallyn
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
I'm wondering if this is actually a bug in the error handling in the encrypted
key type. Looking in the syzbot console log, there's a lot of output from
there prior to the crash, of which the following is an excerpt:
[ 248.516746][T27381] encrypted_key: key user:syz not found
[ 248.524392][T27382] encrypted_key: key user:syz not found
[ 248.616141][T27392] encrypted_key: key user:syz not found
[ 248.618890][T27393] encrypted_key: key user:syz not found
[ 248.690844][T27404] encrypted_key: key user:syz not found
[ 248.739405][T27403] encrypted_key: key user:syz not found
[ 248.804881][T27417] encrypted_key: key user:syz not found
[ 248.828354][T27418] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.925249][T27427] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.928200][T27415] Bad refcount user syz
[ 248.934043][T27428] encrypted_key: key user:syz not found
[ 248.939502][T27429] encrypted_key: key user:syz not found
[ 248.968744][T27434] encrypted_key: key user:syz not found
[ 248.982201][T27415] ==================================================================
[ 248.996072][T27415] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x81/0x200
Note that the "Bad refcount user syz" is a bit I patched in to print the type
and description of the key that incurred the error.
It's a tad difficult to say exactly what's going on since I've no idea what
the syzbot reproducer is actually doing.
#{"threaded":true,"collide":true,"repeat":true,"procs":6,"sandbox":"namespace","fault_call":-1,"tun":true,"netdev":true,"resetnet":true,"cgroups":true,"binfmt_misc":true,"close_fds":true,"tmpdir":true,"segv":true}
perf_event_open(&(0x7f000001d000)={0x1, 0x70, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0x0)
keyctl$instantiate(0xc, 0x0, &(0x7f0000000100)=ANY=[@ANYBLOB='new default user:syz 04096'], 0x1, 0x0)
r0 = add_key(&(0x7f0000000140)='encrypted\x00', &(0x7f0000000180)={'syz'}, &(0x7f0000000100), 0xca, 0xfffffffffffffffe)
add_key$user(&(0x7f0000000040)='user\x00', &(0x7f0000000000)={'syz'}, &(0x7f0000000440)='X', 0x1, 0xfffffffffffffffe)
keyctl$read(0xb, r0, &(0x7f0000000240)=""/112, 0x349b7f55)
However, it looks like the encrypted key type is trying to access a user key,
so maybe there's an overput there? I'm trying to insert more debugging, but
the test doesn't always fail.
syzbot <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> HEAD commit: bc88f85c kthread: make __kthread_queue_delayed_work static
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1730584b600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
> dashboard link: https://syzkaller.appspot.com/bug?extid=6455648abc28dbdd1e7f
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c8adab600000
David
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-22 10:35 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 10:35 UTC (permalink / raw)
To: Linus Torvalds, Mimi Zohar
Cc: dhowells, syzbot, aou, Jarkko Sakkinen,
James Morris James Morris, keyrings, Linux Kernel Mailing List,
linux-riscv, LSM List, Palmer Dabbelt, Serge E. Hallyn,
syzkaller-bugs
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > syzbot has bisected this bug to 0570bc8b7c9b ("Merge tag
> > 'riscv/for-v5.3-rc1' ...")
>
> Yeah, that looks unlikely. The only non-riscv changes are from
> documentation updates and moving a config variable around.
>
> Looks like the crash is quite unlikely, and only happens in one out of
> ten runs for the ones it has happened to.
>
> The backtrace looks simple enough, though:
>
> RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
> __key_get include/linux/key.h:281 [inline]
> find_key_to_update+0x67/0x80 security/keys/keyring.c:1127
> key_create_or_update+0x4e5/0xb20 security/keys/key.c:905
> __do_sys_add_key security/keys/keyctl.c:132 [inline]
> __se_sys_add_key security/keys/keyctl.c:72 [inline]
> __x64_sys_add_key+0x219/0x3f0 security/keys/keyctl.c:72
> do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> which to me implies that there's some locking bug, and somebody
> released the key without holding a lock.
I'm wondering if this is actually a bug in the error handling in the encrypted
key type. Looking in the syzbot console log, there's a lot of output from
there prior to the crash, of which the following is an excerpt:
[ 248.516746][T27381] encrypted_key: key user:syz not found
[ 248.524392][T27382] encrypted_key: key user:syz not found
[ 248.616141][T27392] encrypted_key: key user:syz not found
[ 248.618890][T27393] encrypted_key: key user:syz not found
[ 248.690844][T27404] encrypted_key: key user:syz not found
[ 248.739405][T27403] encrypted_key: key user:syz not found
[ 248.804881][T27417] encrypted_key: key user:syz not found
[ 248.828354][T27418] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.925249][T27427] encrypted_key: keyword 'new' not allowed when called from .update method
[ 248.928200][T27415] Bad refcount user syz
[ 248.934043][T27428] encrypted_key: key user:syz not found
[ 248.939502][T27429] encrypted_key: key user:syz not found
[ 248.968744][T27434] encrypted_key: key user:syz not found
[ 248.982201][T27415] ==================================================================
[ 248.996072][T27415] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x81/0x200
Note that the "Bad refcount user syz" is a bit I patched in to print the type
and description of the key that incurred the error.
It's a tad difficult to say exactly what's going on since I've no idea what
the syzbot reproducer is actually doing.
#{"threaded":true,"collide":true,"repeat":true,"procs":6,"sandbox":"namespace","fault_call":-1,"tun":true,"netdev":true,"resetnet":true,"cgroups":true,"binfmt_misc":true,"close_fds":true,"tmpdir":true,"segv":true}
perf_event_open(&(0x7f000001d000)={0x1, 0x70, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0x0)
keyctl$instantiate(0xc, 0x0, &(0x7f0000000100)=ANY=[@ANYBLOB='new default user:syz 04096'], 0x1, 0x0)
r0 = add_key(&(0x7f0000000140)='encrypted\x00', &(0x7f0000000180)={'syz'}, &(0x7f0000000100), 0xca, 0xfffffffffffffffe)
add_key$user(&(0x7f0000000040)='user\x00', &(0x7f0000000000)={'syz'}, &(0x7f0000000440)='X', 0x1, 0xfffffffffffffffe)
keyctl$read(0xb, r0, &(0x7f0000000240)=""/112, 0x349b7f55)
However, it looks like the encrypted key type is trying to access a user key,
so maybe there's an overput there? I'm trying to insert more debugging, but
the test doesn't always fail.
syzbot <syzbot+6455648abc28dbdd1e7f@syzkaller.appspotmail.com> wrote:
> HEAD commit: bc88f85c kthread: make __kthread_queue_delayed_work static
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1730584b600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
> dashboard link: https://syzkaller.appspot.com/bug?extid=6455648abc28dbdd1e7f
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c8adab600000
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
2019-10-17 2:42 ` syzbot
(?)
@ 2019-10-22 13:17 ` David Howells
-1 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 13:17 UTC (permalink / raw)
To: Mimi Zohar
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Linus Torvalds, Serge E. Hallyn
Okay, I managed to catch a backtrace for this line:
encrypted_key: key user:syz not found (-126)
looking like:
CPU: 0 PID: 8878 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
dump_stack+0x172/0x1f0
request_master_key.isra.0.cold+0x62/0xc3
encrypted_read+0x221/0x830
? get_derived_key+0xf0/0xf0
? keyctl_read_key+0x1c2/0x2b0
? __kasan_check_write+0x14/0x20
? down_read+0x109/0x430
? security_key_permission+0x8d/0xc0
? down_read_killable+0x490/0x490
? key_task_permission+0x1b5/0x3a0
keyctl_read_key+0x231/0x2b0
__x64_sys_keyctl+0x171/0x470
do_syscall_64+0xfa/0x760
entry_SYSCALL_64_after_hwframe+0x49/0xbe
So something somewhere is calling keyctl_read() in userspace on the encrypted
key and that is then referring across to the user key added.
Also, the encrypted key is being given the following payload:
ENCRYPTED: 'new default user:syz 04096'
in at least one of the cases that encrypted_update() being called.
David
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-22 13:17 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 13:17 UTC (permalink / raw)
To: Mimi Zohar
Cc: aou, syzbot, Palmer Dabbelt, syzkaller-bugs,
James Morris James Morris, Jarkko Sakkinen,
Linux Kernel Mailing List, dhowells, LSM List, keyrings,
linux-riscv, Linus Torvalds, Serge E. Hallyn
Okay, I managed to catch a backtrace for this line:
encrypted_key: key user:syz not found (-126)
looking like:
CPU: 0 PID: 8878 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
dump_stack+0x172/0x1f0
request_master_key.isra.0.cold+0x62/0xc3
encrypted_read+0x221/0x830
? get_derived_key+0xf0/0xf0
? keyctl_read_key+0x1c2/0x2b0
? __kasan_check_write+0x14/0x20
? down_read+0x109/0x430
? security_key_permission+0x8d/0xc0
? down_read_killable+0x490/0x490
? key_task_permission+0x1b5/0x3a0
keyctl_read_key+0x231/0x2b0
__x64_sys_keyctl+0x171/0x470
do_syscall_64+0xfa/0x760
entry_SYSCALL_64_after_hwframe+0x49/0xbe
So something somewhere is calling keyctl_read() in userspace on the encrypted
key and that is then referring across to the user key added.
Also, the encrypted key is being given the following payload:
ENCRYPTED: 'new default user:syz 04096'
in at least one of the cases that encrypted_update() being called.
David
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: WARNING: refcount bug in find_key_to_update
@ 2019-10-22 13:17 ` David Howells
0 siblings, 0 replies; 30+ messages in thread
From: David Howells @ 2019-10-22 13:17 UTC (permalink / raw)
To: Mimi Zohar
Cc: dhowells, Linus Torvalds, syzbot, aou, Jarkko Sakkinen,
James Morris James Morris, keyrings, Linux Kernel Mailing List,
linux-riscv, LSM List, Palmer Dabbelt, Serge E. Hallyn,
syzkaller-bugs
Okay, I managed to catch a backtrace for this line:
encrypted_key: key user:syz not found (-126)
looking like:
CPU: 0 PID: 8878 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
dump_stack+0x172/0x1f0
request_master_key.isra.0.cold+0x62/0xc3
encrypted_read+0x221/0x830
? get_derived_key+0xf0/0xf0
? keyctl_read_key+0x1c2/0x2b0
? __kasan_check_write+0x14/0x20
? down_read+0x109/0x430
? security_key_permission+0x8d/0xc0
? down_read_killable+0x490/0x490
? key_task_permission+0x1b5/0x3a0
keyctl_read_key+0x231/0x2b0
__x64_sys_keyctl+0x171/0x470
do_syscall_64+0xfa/0x760
entry_SYSCALL_64_after_hwframe+0x49/0xbe
So something somewhere is calling keyctl_read() in userspace on the encrypted
key and that is then referring across to the user key added.
Also, the encrypted key is being given the following payload:
ENCRYPTED: 'new default user:syz 04096'
in at least one of the cases that encrypted_update() being called.
David
^ permalink raw reply [flat|nested] 30+ messages in thread