Re: kernel/trace/fprobe.c:59 fprobe_handler() error: uninitialized symbol 'ret'.

[Dan Carpenter]

On Wed, May 17, 2023 at 08:45:05PM +0900, Masami Hiramatsu wrote:
> Hi Dan,
> 
> Sorry, I missed my fix :(
> 
> https://lore.kernel.org/all/168100731160.79534.374827110083836722.stgit@devnote2/
> 
> That will fix the problem, could you test it?
> 

It's awkward for me to test it right now...  :(  The fix looks good
to me though and will obviously silence the static checker warning.

Acked-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

regards,
dan carpenter


> Thanks,
> 
> On Mon, 8 May 2023 08:17:09 +0300
> Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   2e1e1337881b0e9844d687982aa54b31b1269b11
> > commit: 39d954200bf6ad503c722e44d0be80c7b826fa42 fprobe: Skip exit_handler if entry_handler returns !0
> > config: i386-randconfig-m041-20230501 (https://download.01.org/0day-ci/archive/20230506/202305061702.6h3JzCPA-lkp@xxxxxxxxx/config)
> > compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
> > 
> > If you fix the issue, kindly add following tag where applicable
> > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > | Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> > | Link: https://lore.kernel.org/r/202305061702.6h3JzCPA-lkp@xxxxxxxxx/
> > 
> > smatch warnings:
> > kernel/trace/fprobe.c:59 fprobe_handler() error: uninitialized symbol 'ret'.
> > 
> > vim +/ret +59 kernel/trace/fprobe.c
> > 
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  23  static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  24  			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  25  {
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  26  	struct fprobe_rethook_node *fpr;
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  27) 	struct rethook_node *rh = NULL;
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  28  	struct fprobe *fp;
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  29) 	void *entry_data = NULL;
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  30) 	int bit, ret;
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  31  
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  32  	fp = container_of(ops, struct fprobe, ops);
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  33  	if (fprobe_disabled(fp))
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  34  		return;
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  35  
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  36  	bit = ftrace_test_recursion_trylock(ip, parent_ip);
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  37  	if (bit < 0) {
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  38  		fp->nmissed++;
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  39  		return;
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  40  	}
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  41  
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  42  	if (fp->exit_handler) {
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  43  		rh = rethook_try_get(fp->rethook);
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  44  		if (!rh) {
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  45  			fp->nmissed++;
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  46  			goto out;
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  47  		}
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  48  		fpr = container_of(rh, struct fprobe_rethook_node, node);
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  49  		fpr->entry_ip = ip;
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  50) 		if (fp->entry_data_size)
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  51) 			entry_data = fpr->data;
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  52  	}
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  53  
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  54) 	if (fp->entry_handler)
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  55) 		ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  56) 
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  57) 	/* If entry_handler returns !0, nmissed is not counted. */
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  58) 	if (rh) {
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02 @59) 		if (ret)
> > 
> > I reported this one earlier.  The code assumes that if there is an
> > -exit_handler there is also an ->entry_handler().  You had said you
> > would just initialized ret = 0;
> > 
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  60) 			rethook_recycle(rh);
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  61) 		else
> > 76d0de5729c056 Masami Hiramatsu (Google  2023-02-02  62) 			rethook_hook(rh, ftrace_get_regs(fregs), true);
> > 39d954200bf6ad Masami Hiramatsu (Google  2023-02-02  63) 	}
> > 5b0ab78998e325 Masami Hiramatsu          2022-03-15  64  out:
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  65  	ftrace_test_recursion_unlock(bit);
> > cad9931f64dc7f Masami Hiramatsu          2022-03-15  66  }
> > 
> > -- 
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests
> > 
> 
> 
> -- 
> Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>