From: Colin King <colin.king@canonical.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
George Dunlap <george.dunlap@eu.citrix.com>
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] perf/x86: Fix integer overflow when left shifting an integer more than 32 bits
Date: Tue, 20 Apr 2021 15:29:07 +0100 [thread overview]
Message-ID: <20210420142907.382417-1-colin.king@canonical.com> (raw)
From: Colin Ian King <colin.king@canonical.com>
The 64 bit value read from MSR_ARCH_PERFMON_FIXED_CTR_CTRL is being
bit-wise masked with the value (0x03 << i*4). However, the shifted value
is evaluated using 32 bit arithmetic, so will overflow when i > 8.
Fix this by making 0x03 a ULL so that the shift is performed using
64 bit arithmetic.
Addresses-Coverity: ("Unintentional integer overflow")
Fixes: a5ebe0ba3dff ("perf/x86: Check all MSRs before passing hw check")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
arch/x86/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index bafd93c54ffa..59c665c8c2e9 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -261,7 +261,7 @@ static bool check_hw_exists(void)
for (i = 0; i < x86_pmu.num_counters_fixed; i++) {
if (fixed_counter_disabled(i))
continue;
- if (val & (0x03 << i*4)) {
+ if (val & (0x03ULL << i*4)) {
bios_fail = 1;
val_fail = val;
reg_fail = reg;
--
2.30.2
next reply other threads:[~2021-04-20 14:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 14:29 Colin King [this message]
2021-04-20 15:03 ` [PATCH] perf/x86: Fix integer overflow when left shifting an integer more than 32 bits Peter Zijlstra
2021-04-20 15:31 ` Peter Zijlstra
2021-04-20 15:34 ` Colin Ian King
2021-04-23 7:10 ` [tip: perf/core] perf/x86: Allow for 8<num_fixed_counters<16 tip-bot2 for Colin Ian King
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