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Subject[PATCH 5.0 058/238] tracing/perf: Use strndup_user() instead of buggy open-coded version
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jann Horn <jannh@google.com>

commit 83540fbc8812a580b6ad8f93f4c29e62e417687e upstream.

The first version of this method was missing the check for
`ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
on error, so there was still a small memory leak in the error case.
Fix it by using strndup_user() instead of open-coding it.

Link: http://lkml.kernel.org/r/20190220165443.152385-1-jannh@google.com

Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/trace/trace_event_perf.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -299,15 +299,13 @@ int perf_uprobe_init(struct perf_event *

if (!p_event->attr.uprobe_path)
return -EINVAL;
- path = kzalloc(PATH_MAX, GFP_KERNEL);
- if (!path)
- return -ENOMEM;
- ret = strncpy_from_user(
- path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
- if (ret == PATH_MAX)
- return -E2BIG;
- if (ret < 0)
- goto out;
+
+ path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
+ PATH_MAX);
+ if (IS_ERR(path)) {
+ ret = PTR_ERR(path);
+ return (ret == -EINVAL) ? -E2BIG : ret;
+ }
if (path[0] == '\0') {
ret = -EINVAL;
goto out;

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