Re: [PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Adrian Hunter]

On 16/07/13 14:53, Jiri Olsa wrote:
> On Tue, Jul 16, 2013 at 09:38:11AM +0300, Adrian Hunter wrote:
>> The size of data retrieved from a sample event must be
>> validated to ensure it does not go past the end of the
>> event.  That was being done sporadically and without
>> considering integer overflows.
>>
>> Signed-off-by: Adrian Hunter 
>> ---
>>  tools/perf/util/evsel.c | 102 
>> ++--
>>  1 file changed, 64 insertions(+), 38 deletions(-)
>>
>> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
>> index 724b75a..20e2ed9 100644
>> --- a/tools/perf/util/evsel.c
>> +++ b/tools/perf/util/evsel.c
>> @@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
>> perf_evsel *evsel,
>>  return 0;
>>  }
>>  
>> -static bool sample_overlap(const union perf_event *event,
>> -   const void *offset, u64 size)
>> +static inline bool overflow_one(const void *endp, const void *offset)
>>  {
>> -const void *base = event;
>> -
>> -if (offset + size > base + event->header.size)
>> -return true;
>> +return offset + sizeof(u64) > endp;
>> +}
>>  
>> -return false;
>> +static inline bool overflow(const void *endp, u16 max_size, const void 
>> *offset,
>> +u64 size)
>> +{
>> +return size > max_size || offset + size > endp;
> 
> hum, does '(size > max_size)' catch anything that would
> not be catched by '(offset + size > endp)' ?

'offset + size' can overflow and end up less than endp

> 
>>  }
>>  
>> +#define OVERFLOW_CHECK_ONE(offset)  \
>> +do {\
>> +if (overflow_one(endp, (offset)))   \
>> +return -EFAULT; \
>> +} while (0)
>> +
>> +#define OVERFLOW_CHECK(offset, size)\
>> +do {\
>> +if (overflow(endp, max_size, (offset), (size))) \
>> +return -EFAULT; \
>> +} while (0)
> 
> I think, it'd be better to have just one overflow check function, like:
> 
> static inline bool overflow(const void *endp, const void *offset, u64 size)
> {
> return offset + size > endp;
> }
> 
> #define OVERFLOW_CHECK(offset, size)\
> do {\
> if (overflow(endp, (offset), (size)))   \
> return -EFAULT; \
> } while (0)
> 
> #define OVERFLOW_CHECK_u64(offset) OVERFLOW_CHECK(offset, sizeof(u64))
> 

OK

>> +
>>  int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event 
>> *event,
>>   struct perf_sample *data)
>>  {
> 
> Hum, I was thinking of making this check more general and
> cover also perf_event__synthesize_sample function.. but
> looks like it's not needed there..?

Currently the caller must ensure there is enough space.

> 
> 
>>  u64 type = evsel->attr.sample_type;
>> -u64 regs_user = evsel->attr.sample_regs_user;
>>  bool swapped = evsel->needs_swap;
>>  const u64 *array;
>> +u16 max_size = event->header.size;
>> +const void *endp = (void *)event + max_size;
>> +u64 sz;
>>  
>>  /*
>>   * used for cross-endian analysis. See git commit 65014ab3
>> @@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel 
>> *evsel, union perf_event *event,
>>  
>>  array = event->sample.array;
>>  
>> +/*
>> + * sample_size is based on PERF_SAMPLE_MASK which includes up to
> 
> please prepend ^^^: The evsel's

OK

> 
>> + * PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
>> + * used to check the format does not go past the end of the event.
>> + */
>>  if (evsel->sample_size + sizeof(event->header) > event->header.size)
>>  return -EFAULT;
>>  

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Re: [PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Adrian Hunter]

On 16/07/13 14:53, Jiri Olsa wrote:
 On Tue, Jul 16, 2013 at 09:38:11AM +0300, Adrian Hunter wrote:
 The size of data retrieved from a sample event must be
 validated to ensure it does not go past the end of the
 event.  That was being done sporadically and without
 considering integer overflows.

 Signed-off-by: Adrian Hunter adrian.hun...@intel.com
 ---
  tools/perf/util/evsel.c | 102 
 ++--
  1 file changed, 64 insertions(+), 38 deletions(-)

 diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
 index 724b75a..20e2ed9 100644
 --- a/tools/perf/util/evsel.c
 +++ b/tools/perf/util/evsel.c
 @@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
 perf_evsel *evsel,
  return 0;
  }
  
 -static bool sample_overlap(const union perf_event *event,
 -   const void *offset, u64 size)
 +static inline bool overflow_one(const void *endp, const void *offset)
  {
 -const void *base = event;
 -
 -if (offset + size  base + event-header.size)
 -return true;
 +return offset + sizeof(u64)  endp;
 +}
  
 -return false;
 +static inline bool overflow(const void *endp, u16 max_size, const void 
 *offset,
 +u64 size)
 +{
 +return size  max_size || offset + size  endp;
 
 hum, does '(size  max_size)' catch anything that would
 not be catched by '(offset + size  endp)' ?

'offset + size' can overflow and end up less than endp

 
  }
  
 +#define OVERFLOW_CHECK_ONE(offset)  \
 +do {\
 +if (overflow_one(endp, (offset)))   \
 +return -EFAULT; \
 +} while (0)
 +
 +#define OVERFLOW_CHECK(offset, size)\
 +do {\
 +if (overflow(endp, max_size, (offset), (size))) \
 +return -EFAULT; \
 +} while (0)
 
 I think, it'd be better to have just one overflow check function, like:
 
 static inline bool overflow(const void *endp, const void *offset, u64 size)
 {
 return offset + size  endp;
 }
 
 #define OVERFLOW_CHECK(offset, size)\
 do {\
 if (overflow(endp, (offset), (size)))   \
 return -EFAULT; \
 } while (0)
 
 #define OVERFLOW_CHECK_u64(offset) OVERFLOW_CHECK(offset, sizeof(u64))
 

OK

 +
  int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event 
 *event,
   struct perf_sample *data)
  {
 
 Hum, I was thinking of making this check more general and
 cover also perf_event__synthesize_sample function.. but
 looks like it's not needed there..?

Currently the caller must ensure there is enough space.

 
 
  u64 type = evsel-attr.sample_type;
 -u64 regs_user = evsel-attr.sample_regs_user;
  bool swapped = evsel-needs_swap;
  const u64 *array;
 +u16 max_size = event-header.size;
 +const void *endp = (void *)event + max_size;
 +u64 sz;
  
  /*
   * used for cross-endian analysis. See git commit 65014ab3
 @@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel 
 *evsel, union perf_event *event,
  
  array = event-sample.array;
  
 +/*
 + * sample_size is based on PERF_SAMPLE_MASK which includes up to
 
 please prepend ^^^: The evsel's

OK

 
 + * PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
 + * used to check the format does not go past the end of the event.
 + */
  if (evsel-sample_size + sizeof(event-header)  event-header.size)
  return -EFAULT;
  

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Re: [PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Jiri Olsa]

On Tue, Jul 16, 2013 at 09:38:11AM +0300, Adrian Hunter wrote:
> The size of data retrieved from a sample event must be
> validated to ensure it does not go past the end of the
> event.  That was being done sporadically and without
> considering integer overflows.
> 
> Signed-off-by: Adrian Hunter 
> ---
>  tools/perf/util/evsel.c | 102 
> ++--
>  1 file changed, 64 insertions(+), 38 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 724b75a..20e2ed9 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
> perf_evsel *evsel,
>   return 0;
>  }
>  
> -static bool sample_overlap(const union perf_event *event,
> -const void *offset, u64 size)
> +static inline bool overflow_one(const void *endp, const void *offset)
>  {
> - const void *base = event;
> -
> - if (offset + size > base + event->header.size)
> - return true;
> + return offset + sizeof(u64) > endp;
> +}
>  
> - return false;
> +static inline bool overflow(const void *endp, u16 max_size, const void 
> *offset,
> + u64 size)
> +{
> + return size > max_size || offset + size > endp;

hum, does '(size > max_size)' catch anything that would
not be catched by '(offset + size > endp)' ?

>  }
>  
> +#define OVERFLOW_CHECK_ONE(offset)   \
> + do {\
> + if (overflow_one(endp, (offset)))   \
> + return -EFAULT; \
> + } while (0)
> +
> +#define OVERFLOW_CHECK(offset, size) \
> + do {\
> + if (overflow(endp, max_size, (offset), (size))) \
> + return -EFAULT; \
> + } while (0)

I think, it'd be better to have just one overflow check function, like:

static inline bool overflow(const void *endp, const void *offset, u64 size)
{
return offset + size > endp;
}

#define OVERFLOW_CHECK(offset, size)\
do {\
if (overflow(endp, (offset), (size)))   \
return -EFAULT; \
} while (0)

#define OVERFLOW_CHECK_u64(offset) OVERFLOW_CHECK(offset, sizeof(u64))

> +
>  int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event 
> *event,
>struct perf_sample *data)
>  {

Hum, I was thinking of making this check more general and
cover also perf_event__synthesize_sample function.. but
looks like it's not needed there..?


>   u64 type = evsel->attr.sample_type;
> - u64 regs_user = evsel->attr.sample_regs_user;
>   bool swapped = evsel->needs_swap;
>   const u64 *array;
> + u16 max_size = event->header.size;
> + const void *endp = (void *)event + max_size;
> + u64 sz;
>  
>   /*
>* used for cross-endian analysis. See git commit 65014ab3
> @@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
> union perf_event *event,
>  
>   array = event->sample.array;
>  
> + /*
> +  * sample_size is based on PERF_SAMPLE_MASK which includes up to

please prepend ^^^: The evsel's

> +  * PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
> +  * used to check the format does not go past the end of the event.
> +  */
>   if (evsel->sample_size + sizeof(event->header) > event->header.size)
>   return -EFAULT;
>  

thanks,
jirka
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[PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Adrian Hunter]

The size of data retrieved from a sample event must be
validated to ensure it does not go past the end of the
event.  That was being done sporadically and without
considering integer overflows.

Signed-off-by: Adrian Hunter 
---
 tools/perf/util/evsel.c | 102 ++--
 1 file changed, 64 insertions(+), 38 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 724b75a..20e2ed9 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
perf_evsel *evsel,
return 0;
 }
 
-static bool sample_overlap(const union perf_event *event,
-  const void *offset, u64 size)
+static inline bool overflow_one(const void *endp, const void *offset)
 {
-   const void *base = event;
-
-   if (offset + size > base + event->header.size)
-   return true;
+   return offset + sizeof(u64) > endp;
+}
 
-   return false;
+static inline bool overflow(const void *endp, u16 max_size, const void *offset,
+   u64 size)
+{
+   return size > max_size || offset + size > endp;
 }
 
+#define OVERFLOW_CHECK_ONE(offset) \
+   do {\
+   if (overflow_one(endp, (offset)))   \
+   return -EFAULT; \
+   } while (0)
+
+#define OVERFLOW_CHECK(offset, size)   \
+   do {\
+   if (overflow(endp, max_size, (offset), (size))) \
+   return -EFAULT; \
+   } while (0)
+
 int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
 struct perf_sample *data)
 {
u64 type = evsel->attr.sample_type;
-   u64 regs_user = evsel->attr.sample_regs_user;
bool swapped = evsel->needs_swap;
const u64 *array;
+   u16 max_size = event->header.size;
+   const void *endp = (void *)event + max_size;
+   u64 sz;
 
/*
 * used for cross-endian analysis. See git commit 65014ab3
@@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
 
array = event->sample.array;
 
+   /*
+* sample_size is based on PERF_SAMPLE_MASK which includes up to
+* PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
+* used to check the format does not go past the end of the event.
+*/
if (evsel->sample_size + sizeof(event->header) > event->header.size)
return -EFAULT;
 
@@ -1221,20 +1240,19 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
}
 
if (type & PERF_SAMPLE_CALLCHAIN) {
-   if (sample_overlap(event, array, sizeof(data->callchain->nr)))
-   return -EFAULT;
-
-   data->callchain = (struct ip_callchain *)array;
+   const u64 max_callchain_nr = UINT64_MAX / sizeof(u64);
 
-   if (sample_overlap(event, array, data->callchain->nr))
+   OVERFLOW_CHECK_ONE(array);
+   data->callchain = (struct ip_callchain *)array++;
+   if (data->callchain->nr > max_callchain_nr)
return -EFAULT;
-
-   array += 1 + data->callchain->nr;
+   sz = data->callchain->nr * sizeof(u64);
+   OVERFLOW_CHECK(array, sz);
+   array = (void *)array + sz;
}
 
if (type & PERF_SAMPLE_RAW) {
-   const u64 *pdata;
-
+   OVERFLOW_CHECK_ONE(array);
u.val64 = *array;
if (WARN_ONCE(swapped,
  "Endianness of raw data not corrected!\n")) {
@@ -1243,65 +1261,73 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
u.val32[0] = bswap_32(u.val32[0]);
u.val32[1] = bswap_32(u.val32[1]);
}
-
-   if (sample_overlap(event, array, sizeof(u32)))
-   return -EFAULT;
-
data->raw_size = u.val32[0];
-   pdata = (void *) array + sizeof(u32);
+   array = (void *)array + sizeof(u32);
 
-   if (sample_overlap(event, pdata, data->raw_size))
-   return -EFAULT;
-
-   data->raw_data = (void *) pdata;
-
-   array = (void *)array + data->raw_size + sizeof(u32);
+   OVERFLOW_CHECK(array, data->raw_size);
+   data->raw_data = (void *)array;
+   array = (void *)array + data->raw_size;
}
 
if (type & PERF_SAMPLE_BRANCH_STACK) {
-   u64 sz;
+   const u64 max_branch_nr = UINT64_MAX /
+ 

[PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Adrian Hunter]

The size of data retrieved from a sample event must be
validated to ensure it does not go past the end of the
event.  That was being done sporadically and without
considering integer overflows.

Signed-off-by: Adrian Hunter adrian.hun...@intel.com
---
 tools/perf/util/evsel.c | 102 ++--
 1 file changed, 64 insertions(+), 38 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 724b75a..20e2ed9 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
perf_evsel *evsel,
return 0;
 }
 
-static bool sample_overlap(const union perf_event *event,
-  const void *offset, u64 size)
+static inline bool overflow_one(const void *endp, const void *offset)
 {
-   const void *base = event;
-
-   if (offset + size  base + event-header.size)
-   return true;
+   return offset + sizeof(u64)  endp;
+}
 
-   return false;
+static inline bool overflow(const void *endp, u16 max_size, const void *offset,
+   u64 size)
+{
+   return size  max_size || offset + size  endp;
 }
 
+#define OVERFLOW_CHECK_ONE(offset) \
+   do {\
+   if (overflow_one(endp, (offset)))   \
+   return -EFAULT; \
+   } while (0)
+
+#define OVERFLOW_CHECK(offset, size)   \
+   do {\
+   if (overflow(endp, max_size, (offset), (size))) \
+   return -EFAULT; \
+   } while (0)
+
 int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
 struct perf_sample *data)
 {
u64 type = evsel-attr.sample_type;
-   u64 regs_user = evsel-attr.sample_regs_user;
bool swapped = evsel-needs_swap;
const u64 *array;
+   u16 max_size = event-header.size;
+   const void *endp = (void *)event + max_size;
+   u64 sz;
 
/*
 * used for cross-endian analysis. See git commit 65014ab3
@@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
 
array = event-sample.array;
 
+   /*
+* sample_size is based on PERF_SAMPLE_MASK which includes up to
+* PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
+* used to check the format does not go past the end of the event.
+*/
if (evsel-sample_size + sizeof(event-header)  event-header.size)
return -EFAULT;
 
@@ -1221,20 +1240,19 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
}
 
if (type  PERF_SAMPLE_CALLCHAIN) {
-   if (sample_overlap(event, array, sizeof(data-callchain-nr)))
-   return -EFAULT;
-
-   data-callchain = (struct ip_callchain *)array;
+   const u64 max_callchain_nr = UINT64_MAX / sizeof(u64);
 
-   if (sample_overlap(event, array, data-callchain-nr))
+   OVERFLOW_CHECK_ONE(array);
+   data-callchain = (struct ip_callchain *)array++;
+   if (data-callchain-nr  max_callchain_nr)
return -EFAULT;
-
-   array += 1 + data-callchain-nr;
+   sz = data-callchain-nr * sizeof(u64);
+   OVERFLOW_CHECK(array, sz);
+   array = (void *)array + sz;
}
 
if (type  PERF_SAMPLE_RAW) {
-   const u64 *pdata;
-
+   OVERFLOW_CHECK_ONE(array);
u.val64 = *array;
if (WARN_ONCE(swapped,
  Endianness of raw data not corrected!\n)) {
@@ -1243,65 +1261,73 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
union perf_event *event,
u.val32[0] = bswap_32(u.val32[0]);
u.val32[1] = bswap_32(u.val32[1]);
}
-
-   if (sample_overlap(event, array, sizeof(u32)))
-   return -EFAULT;
-
data-raw_size = u.val32[0];
-   pdata = (void *) array + sizeof(u32);
+   array = (void *)array + sizeof(u32);
 
-   if (sample_overlap(event, pdata, data-raw_size))
-   return -EFAULT;
-
-   data-raw_data = (void *) pdata;
-
-   array = (void *)array + data-raw_size + sizeof(u32);
+   OVERFLOW_CHECK(array, data-raw_size);
+   data-raw_data = (void *)array;
+   array = (void *)array + data-raw_size;
}
 
if (type  PERF_SAMPLE_BRANCH_STACK) {
-   u64 sz;
+   const u64 max_branch_nr = UINT64_MAX /
+ 

Re: [PATCH V6 05/12] perf tools: tidy up sample parsing overflow checking

[Jiri Olsa]

On Tue, Jul 16, 2013 at 09:38:11AM +0300, Adrian Hunter wrote:
 The size of data retrieved from a sample event must be
 validated to ensure it does not go past the end of the
 event.  That was being done sporadically and without
 considering integer overflows.
 
 Signed-off-by: Adrian Hunter adrian.hun...@intel.com
 ---
  tools/perf/util/evsel.c | 102 
 ++--
  1 file changed, 64 insertions(+), 38 deletions(-)
 
 diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
 index 724b75a..20e2ed9 100644
 --- a/tools/perf/util/evsel.c
 +++ b/tools/perf/util/evsel.c
 @@ -1114,24 +1114,38 @@ static int perf_evsel__parse_id_sample(const struct 
 perf_evsel *evsel,
   return 0;
  }
  
 -static bool sample_overlap(const union perf_event *event,
 -const void *offset, u64 size)
 +static inline bool overflow_one(const void *endp, const void *offset)
  {
 - const void *base = event;
 -
 - if (offset + size  base + event-header.size)
 - return true;
 + return offset + sizeof(u64)  endp;
 +}
  
 - return false;
 +static inline bool overflow(const void *endp, u16 max_size, const void 
 *offset,
 + u64 size)
 +{
 + return size  max_size || offset + size  endp;

hum, does '(size  max_size)' catch anything that would
not be catched by '(offset + size  endp)' ?

  }
  
 +#define OVERFLOW_CHECK_ONE(offset)   \
 + do {\
 + if (overflow_one(endp, (offset)))   \
 + return -EFAULT; \
 + } while (0)
 +
 +#define OVERFLOW_CHECK(offset, size) \
 + do {\
 + if (overflow(endp, max_size, (offset), (size))) \
 + return -EFAULT; \
 + } while (0)

I think, it'd be better to have just one overflow check function, like:

static inline bool overflow(const void *endp, const void *offset, u64 size)
{
return offset + size  endp;
}

#define OVERFLOW_CHECK(offset, size)\
do {\
if (overflow(endp, (offset), (size)))   \
return -EFAULT; \
} while (0)

#define OVERFLOW_CHECK_u64(offset) OVERFLOW_CHECK(offset, sizeof(u64))

 +
  int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event 
 *event,
struct perf_sample *data)
  {

Hum, I was thinking of making this check more general and
cover also perf_event__synthesize_sample function.. but
looks like it's not needed there..?


   u64 type = evsel-attr.sample_type;
 - u64 regs_user = evsel-attr.sample_regs_user;
   bool swapped = evsel-needs_swap;
   const u64 *array;
 + u16 max_size = event-header.size;
 + const void *endp = (void *)event + max_size;
 + u64 sz;
  
   /*
* used for cross-endian analysis. See git commit 65014ab3
 @@ -1153,6 +1167,11 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, 
 union perf_event *event,
  
   array = event-sample.array;
  
 + /*
 +  * sample_size is based on PERF_SAMPLE_MASK which includes up to

please prepend ^^^: The evsel's

 +  * PERF_SAMPLE_PERIOD.  After that overflow_one() or overflow() must be
 +  * used to check the format does not go past the end of the event.
 +  */
   if (evsel-sample_size + sizeof(event-header)  event-header.size)
   return -EFAULT;
  

thanks,
jirka
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