INFO: rcu detected stall in netlink_sendmsg (4)

[David Kahurani]

On Friday, July 24, 2020 at 6:28:05 AM UTC+3 syzbot wrote:

syzbot has bisected this issue to:

commit 5a781ccbd19e4664babcbe4b4ead7aa2b9283d22
Author: Vinicius Costa Gomes <viniciu...@intel.com>
Date: Sat Sep 29 00:59:43 2018 +0000

tc: Add support for configuring the taprio scheduler

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16d46e1b100000
start commit: 7cc2a8ea Merge tag 'block-5.8-2020-07-01' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d46e1b100000
kernel config: https://syzkaller.appspot.com/x/.config?x=7be693511b29b338
dashboard link: https://syzkaller.appspot.com/bug?extid=0fb70e87d8e0ac278fe9
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1023588f100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1647a88f100000

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

lost connection to test machine



Warning: Permanently added '10.128.10.52' (ECDSA) to the list of known hosts.
flag provided but not defined: -optional
Usage of ./syz-fuzzer:
-arch string
target arch (default "amd64")
-collide
collide syscalls to provoke data races (default true)
-cover
collect feedback signals (coverage)
-debug
debug output from executor
-executor string
path to executor binary (default "./syz-executor")
-manager string
manager rpc address
-name string
unique name for manager (default "test")
-os string
target OS (default "linux")
-output string
write programs to none/stdout/dmesg/file (default "stdout")
-pprof string
address to serve pprof profiles
-procs int
number of parallel test processes (default 1)
-runtest
enable program testing mode
-sandbox string
sandbox for fuzzing (none/setuid/namespace/android) (default "none")
-test
enable image testing mode
-threaded
use threaded mode in executor (default true)
-timeout duration
execution timeout
-vv int
verbosity



Tested on:

commit: 3e732ebf Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=591cb9bd5eb1079b
dashboard link: https://syzkaller.appspot.com/bug?extid=0fb70e87d8e0ac278fe9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.

[Dmitry Vyukov]

On Wed, 6 Apr 2022 at 10:09, syzbot
<syzbot+0fb70e...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot tried to test the proposed patch but the build/boot failed:
>
> lost connection to test machine

Humm.. this wasn't supposed to happen. Looking.

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[Dmitry Vyukov]

On Wed, 6 Apr 2022 at 10:13, Dmitry Vyukov <dvy...@google.com> wrote:
>
> On Wed, 6 Apr 2022 at 10:09, syzbot
> <syzbot+0fb70e...@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot tried to test the proposed patch but the build/boot failed:
> >
> > lost connection to test machine
>
> Humm.. this wasn't supposed to happen. Looking.

I think it's this commit messed something wrt optionalFlags handling:
https://github.com/google/syzkaller/commit/db6c071e3e484c984d368f821ef8570839181c91

+Aleksandr, please take a look

[Aleksandr Nogikh]

On Wed, Apr 6, 2022 at 10:21 AM Dmitry Vyukov <dvy...@google.com> wrote:
>
> On Wed, 6 Apr 2022 at 10:13, Dmitry Vyukov <dvy...@google.com> wrote:
> >
> > On Wed, 6 Apr 2022 at 10:09, syzbot
> > <syzbot+0fb70e...@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot tried to test the proposed patch but the build/boot failed:
> > >
> > > lost connection to test machine
> >
> > Humm.. this wasn't supposed to happen. Looking.
>
> I think it's this commit messed something wrt optionalFlags handling:
> https://github.com/google/syzkaller/commit/db6c071e3e484c984d368f821ef8570839181c91
>
> +Aleksandr, please take a look

Yes, there was a small bug. Sent a PR:
https://github.com/google/syzkaller/pull/3064