From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: jolsa@redhat.com, vincent.weaver@maine.edu, hpa@zytor.com,
pmenzel+linux-x86@molgen.mpg.de, linux-kernel@vger.kernel.org,
pmenzel@molgen.mpg.de, tglx@linutronix.de, eranian@google.com,
peterz@infradead.org, alexander.shishkin@linux.intel.com,
mingo@kernel.org, bp@alien8.de, acme@redhat.com,
torvalds@linux-foundation.org
Subject: [tip:perf/urgent] perf/x86/amd/ibs: Don't access non-started event
Date: Tue, 24 Jul 2018 08:01:26 -0700 [thread overview]
Message-ID: <tip-d2753e6b4882a637a0e8fb3b9c2e15f33265300e@git.kernel.org> (raw)
In-Reply-To: <alpine.DEB.2.21.1807200958390.1580@nanos.tec.linutronix.de>
Commit-ID: d2753e6b4882a637a0e8fb3b9c2e15f33265300e
Gitweb: https://git.kernel.org/tip/d2753e6b4882a637a0e8fb3b9c2e15f33265300e
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 20 Jul 2018 10:39:07 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Jul 2018 09:51:10 +0200
perf/x86/amd/ibs: Don't access non-started event
Paul Menzel reported the following bug:
> Enabling the undefined behavior sanitizer and building GNU/Linux 4.18-rc5+
> (with some unrelated commits) with GCC 8.1.0 from Debian Sid/unstable, the
> warning below is shown.
>
> > [ 2.111913]
> > ================================================================================
> > [ 2.111917] UBSAN: Undefined behaviour in arch/x86/events/amd/ibs.c:582:24
> > [ 2.111919] member access within null pointer of type 'struct perf_event'
> > [ 2.111926] CPU: 0 PID: 144 Comm: udevadm Not tainted 4.18.0-rc5-00316-g4864b68cedf2 #104
> > [ 2.111928] Hardware name: ASROCK E350M1/E350M1, BIOS TIMELESS 01/01/1970
> > [ 2.111930] Call Trace:
> > [ 2.111943] dump_stack+0x55/0x89
> > [ 2.111949] ubsan_epilogue+0xb/0x33
> > [ 2.111953] handle_null_ptr_deref+0x7f/0x90
> > [ 2.111958] __ubsan_handle_type_mismatch_v1+0x55/0x60
> > [ 2.111964] perf_ibs_handle_irq+0x596/0x620
The code dereferences event before checking the STARTED bit. Patch
below should cure the issue.
The warning should not trigger, if I analyzed the thing correctly.
(And Paul's testing confirms this.)
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Menzel <pmenzel+linux-x86@molgen.mpg.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1807200958390.1580@nanos.tec.linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/events/amd/ibs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 4b98101209a1..d50bb4dc0650 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -579,7 +579,7 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
{
struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
struct perf_event *event = pcpu->event;
- struct hw_perf_event *hwc = &event->hw;
+ struct hw_perf_event *hwc;
struct perf_sample_data data;
struct perf_raw_record raw;
struct pt_regs regs;
@@ -602,6 +602,10 @@ fail:
return 0;
}
+ if (WARN_ON_ONCE(!event))
+ goto fail;
+
+ hwc = &event->hw;
msr = hwc->config_base;
buf = ibs_data.regs;
rdmsrl(msr, *buf);
prev parent reply other threads:[~2018-07-24 15:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-20 7:49 UBSAN: Undefined behaviour in arch/x86/events/amd/ibs.c:582:24: member access within null pointer of type 'struct perf_event' Paul Menzel
2018-07-20 8:39 ` Thomas Gleixner
2018-07-21 19:38 ` Paul Menzel
2018-07-24 15:01 ` tip-bot for Thomas Gleixner [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=tip-d2753e6b4882a637a0e8fb3b9c2e15f33265300e@git.kernel.org \
--to=tipbot@zytor.com \
--cc=acme@redhat.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=bp@alien8.de \
--cc=eranian@google.com \
--cc=hpa@zytor.com \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=pmenzel+linux-x86@molgen.mpg.de \
--cc=pmenzel@molgen.mpg.de \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=vincent.weaver@maine.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).