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SubjectRe: [PATCH] perf ftrace: Fix the buffer size in __write_tracing_file
Hi Olsa,
What about this fix now? Thanks!

On Tue, Dec 26, 2017 at 05:26:56PM +0800, changbin.du@intel.com wrote:
> From: Changbin Du <changbin.du@intel.com>
>
> The terminal character '\0' should take into account as size of the string
> buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
> '--trace-funcs' options didn't work as expected when the <func> doesn't
> exist.
>
> I didn't dive into kernel ftrace fops, but strace shows that if usersapce
> writes a non-terminated string, the kernel side will return success but
> no filter applied. After this fix in userspace, the kernel will return an
> error.
>
> $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
> 0) 0.140 us | rcu_all_qs();
> 3) 0.304 us | mutex_unlock();
> 0) 0.153 us | find_vma();
> 3) 0.088 us | __fsnotify_parent();
> 0) 6.145 us | handle_mm_fault();
> 3) 0.089 us | fsnotify();
> 3) 0.161 us | __sb_end_write();
> 3) 0.710 us | SyS_close();
> 3) 7.848 us | exit_to_usermode_loop();
>
> On above example, I specified function filter 'abcdefg' but all functions
> are enabled.
>
> Signed-off-by: Changbin Du <changbin.du@intel.com>
> ---
> tools/perf/builtin-ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 25a42ac..2604a64 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append)
> {
> char *file;
> int fd, ret = -1;
> - ssize_t size = strlen(val);
> + ssize_t size = strlen(val) + 1;
> int flags = O_WRONLY;
> char errbuf[512];
>
> --
> 2.7.4
>

--
Thanks,
Changbin Du

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