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tracing/user_events: Prevent same name but different args event

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User processes register name_args for events. If the same name but different
args event are registered. The trace outputs of second event are printed
as the first event. This is incorrect.

Return EADDRINUSE back to the user process if the same name but different args
event has being registered.

Link: https://lore.kernel.org/linux-trace-kernel/20230529032100.286534-1-sunliming@kylinos.cn

Signed-off-by: sunliming <sunliming@kylinos.cn>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
sunliming 2023-05-29 11:21:00 +08:00 committed by Steven Rostedt (Google)
parent aafbb1eeab
commit ba470eebc2
2 changed files with 36 additions and 6 deletions
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36
kernel/trace/trace_events_user.c
View file

@ -1786,6 +1786,8 @@ static int user_event_parse(struct user_event_group *group, char *name,
int ret;
u32 key;
struct user_event *user;
int argc = 0;
char **argv;
/* Prevent dyn_event from racing */
mutex_lock(&event_mutex);
@ -1793,13 +1795,35 @@ static int user_event_parse(struct user_event_group *group, char *name,
mutex_unlock(&event_mutex);
if (user) {
*newuser = user;
/*
* Name is allocated by caller, free it since it already exists.
* Caller only worries about failure cases for freeing.
*/
kfree(name);
if (args) {
argv = argv_split(GFP_KERNEL, args, &argc);
if (!argv) {
ret = -ENOMEM;
goto error;
}
ret = user_fields_match(user, argc, (const char **)argv);
argv_free(argv);
} else
ret = list_empty(&user->fields);
if (ret) {
*newuser = user;
/*
* Name is allocated by caller, free it since it already exists.
* Caller only worries about failure cases for freeing.
*/
kfree(name);
} else {
ret = -EADDRINUSE;
goto error;
}
return 0;
error:
refcount_dec(&user->refcnt);
return ret;
}
user = kzalloc(sizeof(*user), GFP_KERNEL_ACCOUNT);

6
tools/testing/selftests/user_events/ftrace_test.c
View file

@ -228,6 +228,12 @@ TEST_F(user, register_events) {
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
/* Multiple registers to same name but different args should fail */
reg.enable_bit = 29;
reg.name_args = (__u64)"__test_event u32 field1;";
ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(EADDRINUSE, errno);
/* Ensure disabled */
self->enable_fd = open(enable_file, O_RDWR);
ASSERT_NE(-1, self->enable_fd);