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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
        mpe@ellerman.id.au, "Ravi Bangoria" <ravi.bangoria@linux.ibm.com>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        "Arnaldo Carvalho de Melo" <acme@redhat.com>,
        "Ingo Molnar" <mingo@kernel.org>, linuxppc-dev@lists.ozlabs.org,
        "Stephane Eranian" <eranian@google.com>, maddy@linux.vnet.ibm.com,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        "Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
        "Vince Weaver" <vincent.weaver@maine.edu>, acme@kernel.org,
        "Jiri Olsa" <jolsa@redhat.com>,
        "Linus Torvalds" <torvalds@linux-foundation.org>
Date:   Wed, 02 Oct 2019 20:06:51 +0100
Message-ID: <lsq.1570043211.910896713@decadent.org.uk>
Subject: [PATCH 3.16 76/87] perf/ioctl: Add check for the sample_period value
In-Reply-To: <lsq.1570043210.379046399@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.75-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>

commit 913a90bc5a3a06b1f04c337320e9aeee2328dd77 upstream.

perf_event_open() limits the sample_period to 63 bits. See:

  0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits")

Make ioctl() consistent with it.

Also on PowerPC, negative sample_period could cause a recursive
PMIs leading to a hang (reported when running perf-fuzzer).

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: maddy@linux.vnet.ibm.com
Cc: mpe@ellerman.id.au
Fixes: 0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits")
Link: https://lkml.kernel.org/r/20190604042953.914-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 kernel/events/core.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3823,6 +3823,9 @@ static int perf_event_period(struct perf
 	if (perf_event_check_period(event, value))
 		return -EINVAL;
 
+	if (!event->attr.freq && (value & (1ULL << 63)))
+		return -EINVAL;
+
 	task = ctx->task;
 	pe.value = value;