[PATCH 4.4 37/38] perf map: Tighten snprintf() string precision to pass gcc check on some 32-bit arches

Greg Kroah-Hartman
2021-04-15T14:50:38Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

commit 77d02bd00cea9f1a87afe58113fa75b983d6c23a upstream.

Noticed on a debian:experimental mips and mipsel cross build build
environment:

perfbuilder@ec265a086e9b:~$ mips-linux-gnu-gcc --version | head -1
mips-linux-gnu-gcc (Debian 10.2.1-3) 10.2.1 20201224
perfbuilder@ec265a086e9b:~$

CC /tmp/build/perf/util/map.o
util/map.c: In function 'map__new':
util/map.c:109:5: error: '%s' directive output may be truncated writing between 1 and 2147483645 bytes into a region of size 4096 [-Werror=format-truncation=]
109 | "%s/platforms/%s/arch-%s/usr/lib/%s",
| ^~
In file included from /usr/mips-linux-gnu/include/stdio.h:867,
from util/symbol.h:11,
from util/map.c:2:
/usr/mips-linux-gnu/include/bits/stdio2.h:67:10: note: '__builtin___snprintf_chk' output 32 or more bytes (assuming 4294967321) into a destination of size 4096
67 | return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
68 | __bos (__s), __fmt, __va_arg_pack ());
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Since we have the lenghts for what lands in that place, use it to give
the compiler more info and make it happy.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/perf/util/map.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -88,8 +88,7 @@ static inline bool replace_android_lib(c
if (!strncmp(filename, "/system/lib/", 12)) {
char *ndk, *app;
const char *arch;
- size_t ndk_length;
- size_t app_length;
+ int ndk_length, app_length;

ndk = getenv("NDK_ROOT");
app = getenv("APP_PLATFORM");
@@ -117,8 +116,8 @@ static inline bool replace_android_lib(c
if (new_length > PATH_MAX)
return false;
snprintf(newfilename, new_length,
- "%s/platforms/%s/arch-%s/usr/lib/%s",
- ndk, app, arch, libname);
+ "%.*s/platforms/%.*s/arch-%s/usr/lib/%s",
+ ndk_length, ndk, app_length, app, arch, libname);

return true;
}