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From: Leon Romanovsky <leon@kernel.org>
To: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Cc: syzbot <syzbot+26de17458aeda9d305d8@syzkaller.appspotmail.com>,
	linux-rdma@vger.kernel.org, netdev@vger.kernel.org,
	rds-devel@oss.oracle.com, syzkaller-bugs@googlegroups.com,
	davem@davemloft.net, linux-kernel@vger.kernel.org
Subject: Re: WARNING in rds_message_alloc_sgs
Date: Wed, 31 Oct 2018 08:42:20 +0200	[thread overview]
Message-ID: <20181031064220.GN3974@mtr-leonro.mtl.com> (raw)
In-Reply-To: <a7a834e0-c300-b5b9-67b5-78fa3eba8ebb@oracle.com>

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On Tue, Oct 30, 2018 at 12:38:02PM -0700, Santosh Shilimkar wrote:
> On 10/30/2018 12:28 PM, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    6201f31a39f8 Add linux-next specific files for 20181030
> > git tree:       linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1397d06d400000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=2a22859d870756c1
> > dashboard link:
> > https://syzkaller.appspot.com/bug?extid=26de17458aeda9d305d8
> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10bb52eb400000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=118bdfc5400000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+26de17458aeda9d305d8@syzkaller.appspotmail.com
> >
> > WARNING: CPU: 0 PID: 19789 at net/rds/message.c:316
> > rds_message_alloc_sgs+0x10c/0x160 net/rds/message.c:316
> > Kernel panic - not syncing: panic_on_warn set ...
> Looks like this kernel build has panic on warn enabled which
> triggers panic for " WARN_ON(!nr_pages)" case. Will look into
> it. Thanks !!

Please don't forget to remove user triggered WARN_ON.
https://lwn.net/Articles/769365/
"Greg Kroah-Hartman raised the problem of core kernel API code that will
use WARN_ON_ONCE() to complain about bad usage; that will not generate
the desired result if WARN_ON_ONCE() is configured to crash the machine.
He was told that the code should just call pr_warn() instead, and that
the called function should return an error in such situations. It was
generally agreed that any WARN_ON() or WARN_ON_ONCE() calls that can be
triggered from user space need to be fixed."

Thanks

>
> Regards,
> Santosh

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  reply	other threads:[~2018-10-31  6:42 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30 19:28 syzbot
2018-10-30 19:38 ` Santosh Shilimkar
2018-10-31  6:42   ` Leon Romanovsky [this message]
2018-10-31 16:44     ` Santosh Shilimkar

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