linux-kernel - [RFC PATCH v0 06/19] perf/x86/intel/ds: Check insn_get

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Message-Id: <20201124101952.7909-7-bp@alien8.de>
Date:   Tue, 24 Nov 2020 11:19:39 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andy Lutomirski <luto@...capital.net>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH v0 06/19] perf/x86/intel/ds: Check insn_get_length() retval

From: Borislav Petkov <bp@...e.de>

intel_pmu_pebs_fixup_ip() needs only the insn length so use the
appropriate helper instead of a full decode. A full decode differs only
in running insn_complete() on the decoded insn but that is not needed
here.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/events/intel/ds.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index fb327d11a04d..56cbcfee0ab1 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1263,14 +1263,14 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
 		is_64bit = kernel_ip(to) || any_64bit_mode(regs);
 #endif
 		insn_init(&insn, kaddr, size, is_64bit);
-		insn_get_length(&insn);
+
 		/*
 		 * Make sure there was not a problem decoding the
 		 * instruction and getting the length.  This is
 		 * doubly important because we have an infinite
 		 * loop if insn.length=0.
 		 */
-		if (!insn.length)
+		if (insn_get_length(&insn) || !insn.length)
 			break;
 
 		to += insn.length;
-- 
2.21.0