[tip:perf/urgent] perf/x86/regs: Check reserved bits

[tip-bot for Kan Liang <tipbot@zytor.com>]

Commit-ID:  90d424915ab6550826d297fd62df8ee255345b95
Gitweb:     https://git.kernel.org/tip/90d424915ab6550826d297fd62df8ee255345b95
Author:     Kan Liang <kan.liang@linux.intel.com>
AuthorDate: Tue, 28 May 2019 15:08:31 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 24 Jun 2019 19:19:24 +0200

perf/x86/regs: Check reserved bits

The perf fuzzer triggers a warning which map to:

        if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
                return 0;

The bits between XMM registers and generic registers are reserved.
But perf_reg_validate() doesn't check these bits.

Add PERF_REG_X86_RESERVED for reserved bits on X86.
Check the reserved bits in perf_reg_validate().

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Kan Liang <kan.liang@linux.intel.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>
Fixes: 878068ea270e ("perf/x86: Support outputting XMM registers")
Link: https://lkml.kernel.org/r/1559081314-9714-2-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/perf_regs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index 07c30ee17425..bb7e1132290b 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -74,6 +74,9 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 	return regs_get_register(regs, pt_regs_offset[idx]);
 }
 
+#define PERF_REG_X86_RESERVED	(((1ULL << PERF_REG_X86_XMM0) - 1) & \
+				 ~((1ULL << PERF_REG_X86_MAX) - 1))
+
 #ifdef CONFIG_X86_32
 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_R8) | \
 		       (1ULL << PERF_REG_X86_R9) | \
@@ -86,7 +89,7 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 
 int perf_reg_validate(u64 mask)
 {
-	if (!mask || (mask & REG_NOSUPPORT))
+	if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED)))
 		return -EINVAL;
 
 	return 0;
@@ -112,7 +115,7 @@ void perf_get_regs_user(struct perf_regs *regs_user,
 
 int perf_reg_validate(u64 mask)
 {
-	if (!mask || (mask & REG_NOSUPPORT))
+	if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED)))
 		return -EINVAL;
 
 	return 0;