From: Peter Collingbourne <pcc@google.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Helge Deller <deller@gmx.de>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Oleg Nesterov <oleg@redhat.com>,
Linux API <linux-api@vger.kernel.org>,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Kostya Serebryany <kcc@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Andrey Konovalov <andreyknvl@google.com>,
David Spickett <david.spickett@linaro.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>, Dave Martin <Dave.Martin@arm.com>,
Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH v17 3/3] arm64: expose FAR_EL1 tag bits in siginfo
Date: Tue, 17 Nov 2020 11:51:56 -0800 [thread overview]
Message-ID: <CAMn1gO4+nrwNGPqtAr6gPg=zMQ+kCH-e1YWqCz1kZgS6kHZXkA@mail.gmail.com> (raw)
In-Reply-To: <87mtzgcdb7.fsf@x220.int.ebiederm.org>
On Tue, Nov 17, 2020 at 5:40 AM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Peter Collingbourne <pcc@google.com> writes:
>
> > diff --git a/kernel/signal.c b/kernel/signal.c
> > index 8f34819e80de..16be62e6d341 100644
> > --- a/kernel/signal.c
> > +++ b/kernel/signal.c
> > @@ -1650,6 +1650,15 @@ void force_sigsegv(int sig)
> > force_sig(SIGSEGV);
> > }
> >
> > +static void __user *get_si_addr(void __user *addr, unsigned long sig,
> > + unsigned long si_code)
> > +{
> > + if (current->sighand->action[sig - 1].sa.sa_flags & SA_EXPOSE_TAGBITS)
> > + return addr;
>
> Apologies for not seeing this before but this part of the patch is
> buggy.
>
> It is using current->sighand->action when the destination task may not
> be current. send_sig_fault and send_sig_mcerr may somewhat legitimately
> be used to send faults to other processes.
>
> Now that I think about it there are interactions with
> PTRACE_GETSIGINFO/PTRACE_SETSIGINFO.
>
> Can we move the masking into get_signal after the ptrace handling?
>
> That way everything in the core of the kernel deals with unmasked
> si_addr values and we only mask the address just before sending it to
> userspace?
Makes sense, done in v18.
Peter
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next prev parent reply other threads:[~2020-11-17 19:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 3:17 [PATCH v17 0/3] arm64: expose FAR_EL1 tag bits in siginfo Peter Collingbourne
2020-11-17 3:17 ` [PATCH v17 1/3] arch: provide better documentation for the arch-specific SA_* flags Peter Collingbourne
2020-11-17 3:17 ` [PATCH v17 2/3] signal: define the SA_UNSUPPORTED bit in sa_flags Peter Collingbourne
2020-11-17 3:17 ` [PATCH v17 3/3] arm64: expose FAR_EL1 tag bits in siginfo Peter Collingbourne
2020-11-17 13:39 ` Eric W. Biederman
2020-11-17 19:51 ` Peter Collingbourne [this message]
2020-11-17 18:16 ` [PATCH v17 0/3] " Eric W. Biederman
2020-11-17 19:52 ` Peter Collingbourne
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