[axboe:rw_iter 79/471] kernel/trace/trace_events_trigger.c:352 event_trigger_regex_write() warn: potential spectre issue 'buf' [w]

[kernel test robot <lkp@intel.com>]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Jens Axboe <axboe@kernel.dk>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git rw_iter
head:   0a49759be1c3b29207758e467fdc1a90d0716d06
commit: a6f509b8ee48800a6cc81a95554783bf4412a23a [79/471] tracing: convert to read/write iterators
:::::: branch date: 32 hours ago
:::::: commit date: 33 hours ago
config: i386-randconfig-141-20260307 (https://download.01.org/0day-ci/archive/20260308/202603080352.eQSp12OC-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.4.0-5) 12.4.0
smatch: v0.5.0-9004-gb810ac53

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202603080352.eQSp12OC-lkp@intel.com/

smatch warnings:
kernel/trace/trace_events_trigger.c:352 event_trigger_regex_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace_events.c:2246 event_filter_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace_events.c:2404 subsystem_filter_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace.c:4406 tracing_cpumask_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace.c:4686 tracing_trace_options_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace.c:5688 tracing_set_trace_write() warn: potential spectre issue 'buf' [w]
kernel/trace/trace.c:7076 tracing_clock_write() warn: potential spectre issue 'buf' [w]

vim +/buf +352 kernel/trace/trace_events_trigger.c

85f2b08268c014e Tom Zanussi              2013-10-24  331  
a6f509b8ee48800 Jens Axboe               2024-04-08  332  static ssize_t event_trigger_regex_write(struct kiocb *iocb,
a6f509b8ee48800 Jens Axboe               2024-04-08  333  					 struct iov_iter *from)
85f2b08268c014e Tom Zanussi              2013-10-24  334  {
7f1d2f8210195c8 Steven Rostedt (Red Hat  2015-05-05  335) 	struct trace_event_file *event_file;
a6f509b8ee48800 Jens Axboe               2024-04-08  336  	size_t cnt = iov_iter_count(from);
85f2b08268c014e Tom Zanussi              2013-10-24  337  	ssize_t ret;
63c72641683891c Steven Rostedt           2024-12-20  338  	char *buf __free(kfree) = NULL;
85f2b08268c014e Tom Zanussi              2013-10-24  339  
85f2b08268c014e Tom Zanussi              2013-10-24  340  	if (!cnt)
85f2b08268c014e Tom Zanussi              2013-10-24  341  		return 0;
85f2b08268c014e Tom Zanussi              2013-10-24  342  
85f2b08268c014e Tom Zanussi              2013-10-24  343  	if (cnt >= PAGE_SIZE)
85f2b08268c014e Tom Zanussi              2013-10-24  344  		return -EINVAL;
85f2b08268c014e Tom Zanussi              2013-10-24  345  
a6f509b8ee48800 Jens Axboe               2024-04-08  346  	buf = kmalloc(cnt + 1, GFP_KERNEL);
a6f509b8ee48800 Jens Axboe               2024-04-08  347  	if (!buf)
a6f509b8ee48800 Jens Axboe               2024-04-08  348  		return -ENOMEM;
a6f509b8ee48800 Jens Axboe               2024-04-08  349  
a6f509b8ee48800 Jens Axboe               2024-04-08  350  	if (!copy_from_iter_full(buf, cnt, from))
a6f509b8ee48800 Jens Axboe               2024-04-08  351  		return -EFAULT;
a6f509b8ee48800 Jens Axboe               2024-04-08 @352  	buf[cnt] = '\0';
85f2b08268c014e Tom Zanussi              2013-10-24  353  
63c72641683891c Steven Rostedt           2024-12-20  354  	guard(mutex)(&event_mutex);
63c72641683891c Steven Rostedt           2024-12-20  355  
a6f509b8ee48800 Jens Axboe               2024-04-08  356  	event_file = event_file_file(iocb->ki_filp);
63c72641683891c Steven Rostedt           2024-12-20  357  	if (unlikely(!event_file))
85f2b08268c014e Tom Zanussi              2013-10-24  358  		return -ENODEV;
85f2b08268c014e Tom Zanussi              2013-10-24  359  
63c72641683891c Steven Rostedt           2024-12-20  360  	ret = trigger_process_regex(event_file, buf);
85f2b08268c014e Tom Zanussi              2013-10-24  361  	if (ret < 0)
63c72641683891c Steven Rostedt           2024-12-20  362  		return ret;
85f2b08268c014e Tom Zanussi              2013-10-24  363  
a6f509b8ee48800 Jens Axboe               2024-04-08  364  	iocb->ki_pos += cnt;
63c72641683891c Steven Rostedt           2024-12-20  365  	return cnt;
85f2b08268c014e Tom Zanussi              2013-10-24  366  }
85f2b08268c014e Tom Zanussi              2013-10-24  367  

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