Messages in this thread | | | Date | Thu, 21 Feb 2019 09:20:57 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v2] perf/core: use strndup_user() instead of buggy open-coded version |
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Hi Jann,
On Wed, 20 Feb 2019 17:54:43 +0100 Jann Horn <jannh@google.com> wrote:
> 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. >
This looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
BTW, for stable, this is good. For the long term, I think we should fix strndup_user() to return -E2BUG when the user string is longer than max.
Thank you,
> Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()") > Signed-off-by: Jann Horn <jannh@google.com> > --- > v2: > - be compatible with existing error codes (Masami Hiramatsu) > > kernel/trace/trace_event_perf.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c > index 76217bbef815..4629a6104474 100644 > --- 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 *p_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; > -- > 2.21.0.rc0.258.g878e2cd30e-goog >
-- Masami Hiramatsu <mhiramat@kernel.org>
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