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authorMarco Elver <elver@google.com>2022-01-31 13:34:05 +0300
committerPeter Zijlstra <peterz@infradead.org>2022-02-02 15:11:40 +0300
commit3c25fc97f5590060464cabfa25710970ecddbc96 (patch)
tree16a12a50cc2b3d8f07d543968e4145eb096f78e8 /kernel/events
parenta01994f5e5c79d3a35e5e8cf4252c7f2147323c3 (diff)
downloadlinux-3c25fc97f5590060464cabfa25710970ecddbc96.tar.xz
perf: Copy perf_event_attr::sig_data on modification
The intent has always been that perf_event_attr::sig_data should also be modifiable along with PERF_EVENT_IOC_MODIFY_ATTRIBUTES, because it is observable by user space if SIGTRAP on events is requested. Currently only PERF_TYPE_BREAKPOINT is modifiable, and explicitly copies relevant breakpoint-related attributes in hw_breakpoint_copy_attr(). This misses copying perf_event_attr::sig_data. Since sig_data is not specific to PERF_TYPE_BREAKPOINT, introduce a helper to copy generic event-type-independent attributes on modification. Fixes: 97ba62b27867 ("perf: Add support for SIGTRAP on perf events") Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Link: https://lore.kernel.org/r/20220131103407.1971678-1-elver@google.com
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 76c754e45d01..57c7197838db 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3238,6 +3238,15 @@ static int perf_event_modify_breakpoint(struct perf_event *bp,
return err;
}
+/*
+ * Copy event-type-independent attributes that may be modified.
+ */
+static void perf_event_modify_copy_attr(struct perf_event_attr *to,
+ const struct perf_event_attr *from)
+{
+ to->sig_data = from->sig_data;
+}
+
static int perf_event_modify_attr(struct perf_event *event,
struct perf_event_attr *attr)
{
@@ -3260,10 +3269,17 @@ static int perf_event_modify_attr(struct perf_event *event,
WARN_ON_ONCE(event->ctx->parent_ctx);
mutex_lock(&event->child_mutex);
+ /*
+ * Event-type-independent attributes must be copied before event-type
+ * modification, which will validate that final attributes match the
+ * source attributes after all relevant attributes have been copied.
+ */
+ perf_event_modify_copy_attr(&event->attr, attr);
err = func(event, attr);
if (err)
goto out;
list_for_each_entry(child, &event->child_list, child_list) {
+ perf_event_modify_copy_attr(&child->attr, attr);
err = func(child, attr);
if (err)
goto out;