From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v2 20/20] ppc: propagate the calling conventions change down to csum_partial_copy_generic()
Date: Thu, 15 Oct 2020 00:12:10 +0100 [thread overview]
Message-ID: <20201014231210.GM3576660@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAHk-=wgTrpV=mT_EZF1BbWxqezrFJRJcaDtuM58qXMXk9=iaZA@mail.gmail.com>
On Wed, Oct 14, 2020 at 03:51:00PM -0700, Linus Torvalds wrote:
> On Wed, Oct 14, 2020 at 3:27 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> >
> > This patch is causing crashes in WireGuard's CI over at
> > https://www.wireguard.com/build-status/ . Apparently sending a simple
> > network packet winds up triggering refcount_t's warn-on-saturate code. I
>
> Ouch.
>
> The C parts look fairly straightforward, and I don't see how they
> could cause that odd refcount issue.
>
> So I assume it's the low-level asm code conversion that is buggy. And
> it's apparently the 32-bit conversion, since your ppc64 status looks
> fine.
>
> I think it's this instruction:
>
> addi r1,r1,16
>
> that should be removed from the function exit, because Al removed the
>
> - stwu r1,-16(r1)
>
> on function entry.
>
> So I think you end up with a corrupt stack pointer and basically
> random behavior.
Gyahh... ACK, and I really wonder how the hell has it managed to avoid
crashing on testing.
Mea culpa, folks.
next prev parent reply other threads:[~2020-10-15 1:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200724012512.GK2786714@ZenIV.linux.org.uk>
[not found] ` <20200724012546.302155-1-viro@ZenIV.linux.org.uk>
[not found] ` <20200724012546.302155-20-viro@ZenIV.linux.org.uk>
2020-10-14 22:26 ` [PATCH v2 20/20] ppc: propagate the calling conventions change down to csum_partial_copy_generic() Jason A. Donenfeld
2020-10-14 22:51 ` Linus Torvalds
2020-10-14 22:53 ` Linus Torvalds
2020-10-14 22:54 ` Jason A. Donenfeld
2020-10-14 22:53 ` Jason A. Donenfeld
2020-10-14 23:12 ` Al Viro [this message]
2020-10-14 23:02 ` [PATCH] powerpc32: don't adjust unmoved stack pointer in csum_partial_copy_generic() epilogue Jason A. Donenfeld
2020-10-14 23:05 ` Linus Torvalds
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