tree:   https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git  ftrace/core
head:   3dc65994e3c1c999be3d991cdc96705e167cb3b1
commit: 5d4648a0415efc239ffb377bce1d389723eda25d [35/39] tracing/boot: Show correct histogram error command
config: x86_64-randconfig-m001-20210831 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
kernel/trace/trace_boot.c:420 trace_boot_init_histograms() warn: curly braces intended?
kernel/trace/trace_boot.c:421 trace_boot_init_histograms() error: uninitialized symbol 'tmp'.
kernel/trace/trace_boot.c:421 trace_boot_init_histograms() warn: passing freed memory 'tmp'
kernel/trace/trace_boot.c:422 trace_boot_init_histograms() error: double free of 'tmp'

vim +420 kernel/trace/trace_boot.c

30cb856e3067e5d Masami Hiramatsu 2021-08-06  396  static void __init
30cb856e3067e5d Masami Hiramatsu 2021-08-06  397  trace_boot_init_histograms(struct trace_event_file *file,
30cb856e3067e5d Masami Hiramatsu 2021-08-06  398  			   struct xbc_node *hnode, char *buf, size_t size)
30cb856e3067e5d Masami Hiramatsu 2021-08-06  399  {
30cb856e3067e5d Masami Hiramatsu 2021-08-06  400  	struct xbc_node *node;
30cb856e3067e5d Masami Hiramatsu 2021-08-06  401  	const char *p;
5d4648a0415efc2 Masami Hiramatsu 2021-08-06  402  	char *tmp;
30cb856e3067e5d Masami Hiramatsu 2021-08-06  403  
30cb856e3067e5d Masami Hiramatsu 2021-08-06  404  	xbc_node_for_each_subkey(hnode, node) {
30cb856e3067e5d Masami Hiramatsu 2021-08-06  405  		p = xbc_node_get_data(node);
30cb856e3067e5d Masami Hiramatsu 2021-08-06  406  		if (!isdigit(p[0]))
30cb856e3067e5d Masami Hiramatsu 2021-08-06  407  			continue;
30cb856e3067e5d Masami Hiramatsu 2021-08-06  408  		/* All digit started node should be instances. */
30cb856e3067e5d Masami Hiramatsu 2021-08-06  409  		if (trace_boot_compose_hist_cmd(node, buf, size) == 0) {
5d4648a0415efc2 Masami Hiramatsu 2021-08-06  410  			tmp = kstrdup(buf, GFP_KERNEL);
30cb856e3067e5d Masami Hiramatsu 2021-08-06  411  			if (trigger_process_regex(file, buf) < 0)
5d4648a0415efc2 Masami Hiramatsu 2021-08-06  412  				pr_err("Failed to apply hist trigger: %s\n", tmp);
5d4648a0415efc2 Masami Hiramatsu 2021-08-06  413  			kfree(tmp);
30cb856e3067e5d Masami Hiramatsu 2021-08-06  414  		}
30cb856e3067e5d Masami Hiramatsu 2021-08-06  415  	}
30cb856e3067e5d Masami Hiramatsu 2021-08-06  416  
30cb856e3067e5d Masami Hiramatsu 2021-08-06  417  	if (xbc_node_find_child(hnode, "keys")) {
30cb856e3067e5d Masami Hiramatsu 2021-08-06  418  		if (trace_boot_compose_hist_cmd(hnode, buf, size) == 0)

The missing curly braces here trigger a ball of static checker warnings.
I'm so happy about that.  :)

5d4648a0415efc2 Masami Hiramatsu 2021-08-06  419  			tmp = kstrdup(buf, GFP_KERNEL);
30cb856e3067e5d Masami Hiramatsu 2021-08-06 @420  			if (trigger_process_regex(file, buf) < 0)
5d4648a0415efc2 Masami Hiramatsu 2021-08-06 @421  				pr_err("Failed to apply hist trigger: %s\n", tmp);
5d4648a0415efc2 Masami Hiramatsu 2021-08-06 @422  			kfree(tmp);
30cb856e3067e5d Masami Hiramatsu 2021-08-06  423  	}

---
0-DAY CI Kernel Test Service, Intel Corporation
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