From: Marco Elver elver@google.com
[ Upstream commit 3c25fc97f5590060464cabfa25710970ecddbc96 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/core.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 6ed890480c4aa..04e6e2dae60e4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3234,6 +3234,15 @@ 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) { @@ -3256,10 +3265,17 @@ 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;