[PATCH 3/3] perf evsel: Do not access outside hw cache name arrays

Arnaldo Carvalho de Melo
2016-08-19T03:47:35Z

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

We have to check if the values are >= *_MAX, not just >, fix it.

>From the bugzilla report:

''In file /tools/perf/util/evsel.c function __perf_evsel__hw_cache_name
it appears that there is a bug that reads beyond the end of the buffer.
The statement "if (type > PERF_COUNT_HW_CACHE_MAX)" allows type to be
equal to the maximum value. Later, when statement "if
(!perf_evsel__is_cache_op_valid(type, op))" is executed, the function
can access array perf_evsel__hw_cache_stat[type] beyond the end of the
buffer.

It appears to me that the statement "if (type > PERF_COUNT_HW_CACHE_MAX)"
should be "if (type >= PERF_COUNT_HW_CACHE_MAX)"

Bug found with Coverity and manual code review. No attempts were made to
execute the code with a maximum type value.''

Committer note:

Testing it:

$ perf record -e $(echo $(perf list cache | cut -d \[ -f1) | sed 's/ /,/g') usleep 1
[ perf record: Woken up 16 times to write data ]
[ perf record: Captured and wrote 0.023 MB perf.data (34 samples) ]
$ perf evlist
L1-dcache-load-misses
L1-dcache-loads
L1-dcache-stores
L1-icache-load-misses
LLC-load-misses
LLC-loads
LLC-store-misses
LLC-stores
branch-load-misses
branch-loads
dTLB-load-misses
dTLB-loads
dTLB-store-misses
dTLB-stores
iTLB-load-misses
iTLB-loads
node-load-misses
node-loads
node-store-misses
node-stores
$ perf list cache

List of pre-defined events (to be used in -e):

L1-dcache-load-misses [Hardware cache event]
L1-dcache-loads [Hardware cache event]
L1-dcache-stores [Hardware cache event]
L1-icache-load-misses [Hardware cache event]
LLC-load-misses [Hardware cache event]
LLC-loads [Hardware cache event]
LLC-store-misses [Hardware cache event]
LLC-stores [Hardware cache event]
branch-load-misses [Hardware cache event]
branch-loads [Hardware cache event]
dTLB-load-misses [Hardware cache event]
dTLB-loads [Hardware cache event]
dTLB-store-misses [Hardware cache event]
dTLB-stores [Hardware cache event]
iTLB-load-misses [Hardware cache event]
iTLB-loads [Hardware cache event]
node-load-misses [Hardware cache event]
node-loads [Hardware cache event]
node-store-misses [Hardware cache event]
node-stores [Hardware cache event]
$

Reported-by: Brian Sweeney <bsweeney@lgsinnovations.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=153351
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evsel.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d9b80ef881cd..21fd573106ed 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -507,17 +507,17 @@ static int __perf_evsel__hw_cache_name(u64 config, char *bf, size_t size)
u8 op, result, type = (config >> 0) & 0xff;
const char *err = "unknown-ext-hardware-cache-type";

- if (type > PERF_COUNT_HW_CACHE_MAX)
+ if (type >= PERF_COUNT_HW_CACHE_MAX)
goto out_err;

op = (config >> 8) & 0xff;
err = "unknown-ext-hardware-cache-op";
- if (op > PERF_COUNT_HW_CACHE_OP_MAX)
+ if (op >= PERF_COUNT_HW_CACHE_OP_MAX)
goto out_err;

result = (config >> 16) & 0xff;
err = "unknown-ext-hardware-cache-result";
- if (result > PERF_COUNT_HW_CACHE_RESULT_MAX)
+ if (result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
goto out_err;

err = "invalid-cache";
--
2.7.4