[tip:perf/urgent] perf dwarf: Fix potential array out of bounds access

[tip-bot for Wang Nan <tipbot@zytor.com>]

Commit-ID:  3b27d13940c3710a1128527c43719cb0bb05d73b
Gitweb:     http://git.kernel.org/tip/3b27d13940c3710a1128527c43719cb0bb05d73b
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Tue, 1 Sep 2015 03:29:44 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 1 Sep 2015 11:33:48 -0300

perf dwarf: Fix potential array out of bounds access

There is a problem in the dwarf-regs.c files for sh, sparc and x86 where
it is possible to make an out-of-bounds array access when searching for
register names.

This patch fixes it by replacing '<=' to '<', so when register (number
== XXX_MAX_REGS), get_arch_regstr() will return NULL.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Matt Fleming <matt@console-pimps.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@huawei.com
Link: http://lkml.kernel.org/r/1441078184-105038-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/arch/sh/util/dwarf-regs.c    | 2 +-
 tools/perf/arch/sparc/util/dwarf-regs.c | 2 +-
 tools/perf/arch/x86/util/dwarf-regs.c   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/arch/sh/util/dwarf-regs.c b/tools/perf/arch/sh/util/dwarf-regs.c
index 0d0897f..f8dfa89 100644
--- a/tools/perf/arch/sh/util/dwarf-regs.c
+++ b/tools/perf/arch/sh/util/dwarf-regs.c
@@ -51,5 +51,5 @@ const char *sh_regs_table[SH_MAX_REGS] = {
 /* Return architecture dependent register string (for kprobe-tracer) */
 const char *get_arch_regstr(unsigned int n)
 {
-	return (n <= SH_MAX_REGS) ? sh_regs_table[n] : NULL;
+	return (n < SH_MAX_REGS) ? sh_regs_table[n] : NULL;
 }
diff --git a/tools/perf/arch/sparc/util/dwarf-regs.c b/tools/perf/arch/sparc/util/dwarf-regs.c
index 92eda41..b704fdb 100644
--- a/tools/perf/arch/sparc/util/dwarf-regs.c
+++ b/tools/perf/arch/sparc/util/dwarf-regs.c
@@ -39,5 +39,5 @@ const char *sparc_regs_table[SPARC_MAX_REGS] = {
  */
 const char *get_arch_regstr(unsigned int n)
 {
-	return (n <= SPARC_MAX_REGS) ? sparc_regs_table[n] : NULL;
+	return (n < SPARC_MAX_REGS) ? sparc_regs_table[n] : NULL;
 }
diff --git a/tools/perf/arch/x86/util/dwarf-regs.c b/tools/perf/arch/x86/util/dwarf-regs.c
index be22dd4..a08de0a 100644
--- a/tools/perf/arch/x86/util/dwarf-regs.c
+++ b/tools/perf/arch/x86/util/dwarf-regs.c
@@ -71,5 +71,5 @@ const char *x86_64_regs_table[X86_64_MAX_REGS] = {
 /* Return architecture dependent register string (for kprobe-tracer) */
 const char *get_arch_regstr(unsigned int n)
 {
-	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
+	return (n < ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
 }