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perf evlist: Fix perf_evlist__mmap_read event overflow 

The perf_evlist__mmap_read used 'union perf_event' as a placeholder for
event crossing the mmap boundary.

This is ok for sample shorter than ~PATH_MAX. However we could grow up
to the maximum sample size which is 16 bits max.

I hit this overflow issue when using 'perf top -G dwarf' which produces
sample with the size around 8192 bytes.  We could configure any valid
sample size here using: '-G dwarf,size'.

Using array with sample max size instead for the event placeholder. Also
adding another safe check for the dynamic size of the user stack.

TODO: The 'struct perf_mmap' is quite big now, maybe we could use some
lazy allocation for event_copy size.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1380721599-24285-1-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2013-10-02 15:46:39 +02:00 committed by Arnaldo Carvalho de Melo
parent b81a48ea87
commit a65cb4b9f8
4 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
tools/perf/util/event.h
View File

@ -75,6 +75,9 @@ struct throttle_event {
PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD | \ PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD | \
PERF_SAMPLE_IDENTIFIER) PERF_SAMPLE_IDENTIFIER)
/* perf sample has 16 bits size limit */
#define PERF_SAMPLE_MAX_SIZE (1 << 16)
struct sample_event { struct sample_event {
struct perf_event_header header; struct perf_event_header header;
u64 array[]; u64 array[];

4
tools/perf/util/evlist.c
View File

@ -540,7 +540,7 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
if ((old & md->mask) + size != ((old + size) & md->mask)) { if ((old & md->mask) + size != ((old + size) & md->mask)) {
unsigned int offset = old; unsigned int offset = old;
unsigned int len = min(sizeof(*event), size), cpy; unsigned int len = min(sizeof(*event), size), cpy;
void *dst = &md->event_copy; void *dst = md->event_copy;
do { do {
cpy = min(md->mask + 1 - (offset & md->mask), len); cpy = min(md->mask + 1 - (offset & md->mask), len);
@ -550,7 +550,7 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
len -= cpy; len -= cpy;
} while (len); } while (len);
event = &md->event_copy; event = (union perf_event *) md->event_copy;
} }
old += size; old += size;

2
tools/perf/util/evlist.h
View File

@ -21,7 +21,7 @@ struct perf_mmap {
void *base; void *base;
int mask; int mask;
unsigned int prev; unsigned int prev;
union perf_event event_copy; char event_copy[PERF_SAMPLE_MAX_SIZE];
}; };
struct perf_evlist { struct perf_evlist {

3
tools/perf/util/evsel.c
View File

@ -1456,6 +1456,9 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
array = (void *)array + sz; array = (void *)array + sz;
OVERFLOW_CHECK_u64(array); OVERFLOW_CHECK_u64(array);
data->user_stack.size = *array++; data->user_stack.size = *array++;
if (WARN_ONCE(data->user_stack.size > sz,
"user stack dump failure\n"))
return -EFAULT;
} }
} }