On 10/12/2021 13:38, Arnaldo Carvalho de Melo wrote:
> Em Fri, Dec 10, 2021 at 02:47:49PM +0530, kajoljain escreveu:
>>
>> On 12/1/21 6:03 PM, German Gomez wrote:
>>> The size of the cache of register values is arch-dependant
>>> (PERF_REGS_MAX). This has the potential of causing an out-of-bounds
>>> access in the function "perf_reg_value" if the local architecture
>>> contains less registers than the one the perf.data file was recorded on.
>>>
>>> Since the maximum number of registers is bound by the bitmask "u64
>>> cache_mask", and the size of the cache when running under x86 systems is
>>> 64 already, fix the size to 64 and add a range-check to the function
>>> "perf_reg_value" to prevent out-of-bounds access.
>>>
>> Patch looks good to me.
>>
>> Reviewed-by: Kajol Jain<kjain@xxxxxxxxxxxxx>
> Thanks, applied.
>
> - Arnaldo
Thanks Arnaldo, and the rest for the review.
I did send a v2 of this patch afterwards. The only difference was to
give credit to the reporter in the commit message with:
Reported-by: Alexandre Truong <alexandre.truong@xxxxxxx>
Thanks,
German
>
>> Thanks,
>> Kajol Jain
>>
>>> Signed-off-by: German Gomez <german.gomez@xxxxxxx>
>>> ---
>>> tools/perf/util/event.h | 5 ++++-
>>> tools/perf/util/perf_regs.c | 3 +++
>>> 2 files changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
>>> index 95ffed663..c59331eea 100644
>>> --- a/tools/perf/util/event.h
>>> +++ b/tools/perf/util/event.h
>>> @@ -44,13 +44,16 @@ struct perf_event_attr;
>>> /* perf sample has 16 bits size limit */
>>> #define PERF_SAMPLE_MAX_SIZE (1 << 16)
>>>
>>> +/* number of register is bound by the number of bits in regs_dump::mask (64) */
>>> +#define PERF_SAMPLE_REGS_CACHE_SIZE (8 * sizeof(u64))
>>> +
>>> struct regs_dump {
>>> u64 abi;
>>> u64 mask;
>>> u64 *regs;
>>>
>>> /* Cached values/mask filled by first register access. */
>>> - u64 cache_regs[PERF_REGS_MAX];
>>> + u64 cache_regs[PERF_SAMPLE_REGS_CACHE_SIZE];
>>> u64 cache_mask;
>>> };
>>>
>>> diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c
>>> index 5ee47ae15..06a7461ba 100644
>>> --- a/tools/perf/util/perf_regs.c
>>> +++ b/tools/perf/util/perf_regs.c
>>> @@ -25,6 +25,9 @@ int perf_reg_value(u64 *valp, struct regs_dump *regs, int id)
>>> int i, idx = 0;
>>> u64 mask = regs->mask;
>>>
>>> + if ((u64)id >= PERF_SAMPLE_REGS_CACHE_SIZE)
>>> + return -EINVAL;
>>> +
>>> if (regs->cache_mask & (1ULL << id))
>>> goto out;
>>>
>>>
