[tip:perfcounters/core] perf report: Add validation of call-chain entries

tip-bot for Ingo Molnar
2009-06-18T07:22:44Z

Commit-ID: 7522060c95395f479ee4a6af3bbf9e097e92e48f
Gitweb: http://git.kernel.org/tip/7522060c95395f479ee4a6af3bbf9e097e92e48f
Author: Ingo Molnar <mingo@elte.hu>
AuthorDate: Thu, 18 Jun 2009 08:00:17 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 18 Jun 2009 08:15:47 +0200

perf report: Add validation of call-chain entries

Add boundary checks for call-chain events. In case of corrupted
entries we could crash otherwise.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
include/linux/perf_counter.h | 20 ++++++------
tools/perf/builtin-report.c | 74 ++++++++++++++++++++++++++----------------
2 files changed, 56 insertions(+), 38 deletions(-)

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index eccae43..a7d3a61 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -337,6 +337,16 @@ enum perf_event_type {
*/
};

+#define MAX_STACK_DEPTH 255
+
+struct perf_callchain_entry {
+ __u16 nr;
+ __u16 hv;
+ __u16 kernel;
+ __u16 user;
+ __u64 ip[MAX_STACK_DEPTH];
+};
+
#ifdef __KERNEL__
/*
* Kernel-internal data types and definitions:
@@ -652,16 +662,6 @@ extern void perf_counter_fork(struct task_struct *tsk);

extern void perf_counter_task_migration(struct task_struct *task, int cpu);

-#define MAX_STACK_DEPTH 255
-
-struct perf_callchain_entry {
- u16 nr;
- u16 hv;
- u16 kernel;
- u16 user;
- u64 ip[MAX_STACK_DEPTH];
-};
-
extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);

extern int sysctl_perf_counter_paranoid;
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 9868346..e14e986 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -39,6 +39,8 @@ static int dump_trace = 0;
#define cdprintf(x...) do { if (dump_trace) color_fprintf(stdout, color, x); } while (0)

static int verbose;
+#define eprintf(x...) do { if (verbose) fprintf(stderr, x); } while (0)
+
static int full_paths;

static unsigned long page_size;
@@ -47,14 +49,6 @@ static unsigned long mmap_window = 32;
static char *parent_pattern = "^sys_|^do_page_fault";
static regex_t parent_regex;

-struct ip_chain_event {
- __u16 nr;
- __u16 hv;
- __u16 kernel;
- __u16 user;
- __u64 ips[];
-};
-
struct ip_event {
struct perf_event_header header;
__u64 ip;
@@ -131,15 +125,11 @@ static struct dso *dsos__findnew(const char *name)

nr = dso__load(dso, NULL, verbose);
if (nr < 0) {
- if (verbose)
- fprintf(stderr, "Failed to open: %s\n", name);
+ eprintf("Failed to open: %s\n", name);
goto out_delete_dso;
}
- if (!nr && verbose) {
- fprintf(stderr,
- "No symbols found in: %s, maybe install a debug package?\n",
- name);
- }
+ if (!nr)
+ eprintf("No symbols found in: %s, maybe install a debug package?\n", name);

dsos__add(dso);

@@ -844,7 +834,7 @@ static struct symbol *call__match(struct symbol *sym)

static int
hist_entry__add(struct thread *thread, struct map *map, struct dso *dso,
- struct symbol *sym, __u64 ip, struct ip_chain_event *chain,
+ struct symbol *sym, __u64 ip, struct perf_callchain_entry *chain,
char level, __u64 count)
{
struct rb_node **p = &hist.rb_node;
@@ -868,7 +858,7 @@ hist_entry__add(struct thread *thread, struct map *map, struct dso *dso,
__u64 ip;

for (i = 0; i < chain->kernel; i++) {
- ip = chain->ips[nr + i];
+ ip = chain->ip[nr + i];
dso = kernel_dso;
sym = resolve_symbol(thread, NULL, &dso, &ip);
entry.parent = call__match(sym);
@@ -878,7 +868,7 @@ hist_entry__add(struct thread *thread, struct map *map, struct dso *dso,
nr += i;

for (i = 0; i < chain->user; i++) {
- ip = chain->ips[nr + i];
+ ip = chain->ip[nr + i];
sym = resolve_symbol(thread, NULL, NULL, &ip);
entry.parent = call__match(sym);
if (entry.parent)
@@ -1080,6 +1070,30 @@ static unsigned long total = 0,
total_fork = 0,
total_unknown = 0;

+static int validate_chain(struct perf_callchain_entry *chain, event_t *event)
+{
+ unsigned int chain_size;
+
+ if (chain->nr > MAX_STACK_DEPTH)
+ return -1;
+ if (chain->hv > MAX_STACK_DEPTH)
+ return -1;
+ if (chain->kernel > MAX_STACK_DEPTH)
+ return -1;
+ if (chain->user > MAX_STACK_DEPTH)
+ return -1;
+ if (chain->hv + chain->kernel + chain->user != chain->nr)
+ return -1;
+
+ chain_size = event->header.size;
+ chain_size -= (unsigned long)&event->ip.__more_data - (unsigned long)event;
+
+ if (chain->nr*sizeof(__u64) > chain_size)
+ return -1;
+
+ return 0;
+}
+
static int
process_overflow_event(event_t *event, unsigned long offset, unsigned long head)
{
@@ -1091,7 +1105,7 @@ process_overflow_event(event_t *event, unsigned long offset, unsigned long head)
__u64 period = 1;
struct map *map = NULL;
void *more_data = event->ip.__more_data;
- struct ip_chain_event *chain = NULL;
+ struct perf_callchain_entry *chain = NULL;

if (event->header.type & PERF_SAMPLE_PERIOD) {
period = *(__u64 *)more_data;
@@ -1111,21 +1125,26 @@ process_overflow_event(event_t *event, unsigned long offset, unsigned long head)

chain = (void *)more_data;

- if (dump_trace) {
- dprintf("... chain: u:%d, k:%d, nr:%d\n",
- chain->user,
- chain->kernel,
- chain->nr);
+ dprintf("... chain: u:%d, k:%d, nr:%d\n",
+ chain->user,
+ chain->kernel,
+ chain->nr);

+ if (validate_chain(chain, event) < 0) {
+ eprintf("call-chain problem with event, skipping it.\n");
+ return 0;
+ }
+
+ if (dump_trace) {
for (i = 0; i < chain->nr; i++)
- dprintf("..... %2d: %016Lx\n", i, chain->ips[i]);
+ dprintf("..... %2d: %016Lx\n", i, chain->ip[i]);
}
}

dprintf(" ... thread: %s:%d\n", thread->comm, thread->pid);

if (thread == NULL) {
- fprintf(stderr, "problem processing %d event, skipping it.\n",
+ eprintf("problem processing %d event, skipping it.\n",
event->header.type);
return -1;
}
@@ -1153,8 +1172,7 @@ process_overflow_event(event_t *event, unsigned long offset, unsigned long head)
struct symbol *sym = resolve_symbol(thread, &map, &dso, &ip);

if (hist_entry__add(thread, map, dso, sym, ip, chain, level, period)) {
- fprintf(stderr,
- "problem incrementing symbol count, skipping event\n");
+ eprintf("problem incrementing symbol count, skipping event\n");
return -1;
}
}