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SubjectRe: [PATCH 2/2] tracing/probes: make match function safe
Masami and Tom, what are you thoughts on this?

-- Steve

On Sun, May 01, 2022 at 05:34:11PM +0800, Linyu Yuan wrote:
> When delete one kprobe/uprobe/eprobe event entry
> using /sys/kernel/debug/tracing/dynamic_events file,
> it will loop all dynamic envent entries,
> as user will not input dyn_event_operations type,
> when call the match function of kprobe/uprobe/eprobe,
> the dynamic event may have different dyn_event_operations type,
> but currently match function may return a match.
>
> Fix by check dyn_event_operations type first.
>
> Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
> ---
> kernel/trace/trace_eprobe.c | 31 +++++++++++++++++++++++--------
> kernel/trace/trace_kprobe.c | 3 +++
> kernel/trace/trace_uprobe.c | 3 +++
> 3 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index b16e067..0029840 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -19,6 +19,21 @@
>
> #define EPROBE_EVENT_SYSTEM "eprobes"
>
> +static int eprobe_dyn_event_create(const char *raw_command);
> +static int eprobe_dyn_event_show(struct seq_file *m, struct dyn_event *ev);
> +static bool eprobe_dyn_event_is_busy(struct dyn_event *ev);
> +static int eprobe_dyn_event_release(struct dyn_event *ev);
> +static bool eprobe_dyn_event_match(const char *system, const char *event,
> + int argc, const char **argv, struct dyn_event *ev);
> +
> +static struct dyn_event_operations eprobe_dyn_event_ops = {
> + .create = eprobe_dyn_event_create,
> + .show = eprobe_dyn_event_show,
> + .is_busy = eprobe_dyn_event_is_busy,
> + .free = eprobe_dyn_event_release,
> + .match = eprobe_dyn_event_match,
> +};
> +
> struct trace_eprobe {
> /* tracepoint system */
> const char *event_system;
> @@ -39,6 +54,11 @@ struct eprobe_data {
>
> static int __trace_eprobe_create(int argc, const char *argv[]);
>
> +static bool is_trace_eprobe(struct dyn_event *ev)
> +{
> + return ev->ops == &eprobe_dyn_event_ops;
> +}
> +
> static void trace_event_probe_cleanup(struct trace_eprobe *ep)
> {
> if (!ep)
> @@ -121,6 +141,9 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> struct trace_eprobe *ep = to_trace_eprobe(ev);
> const char *slash;
>
> + if (!is_trace_eprobe(ev))
> + return false;
> +
> /*
> * We match the following:
> * event only - match all eprobes with event name
> @@ -174,14 +197,6 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
> return trace_probe_match_command_args(&ep->tp, argc, argv);
> }
>
> -static struct dyn_event_operations eprobe_dyn_event_ops = {
> - .create = eprobe_dyn_event_create,
> - .show = eprobe_dyn_event_show,
> - .is_busy = eprobe_dyn_event_is_busy,
> - .free = eprobe_dyn_event_release,
> - .match = eprobe_dyn_event_match,
> -};
> -
> static struct trace_eprobe *alloc_event_probe(const char *group,
> const char *this_event,
> struct trace_event_call *event,
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 2cd8ef9..f63abfa 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -163,6 +163,9 @@ static bool trace_kprobe_match(const char *system, const char *event,
> {
> struct trace_kprobe *tk = to_trace_kprobe(ev);
>
> + if (!is_trace_kprobe(ev))
> + return false;
> +
> return (event[0] == '\0' ||
> strcmp(trace_probe_name(&tk->tp), event) == 0) &&
> (!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index a935c08..ee55ed0 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -312,6 +312,9 @@ static bool trace_uprobe_match(const char *system, const char *event,
> {
> struct trace_uprobe *tu = to_trace_uprobe(ev);
>
> + if (!is_trace_uprobe(ev))
> + return false;
> +
> return (event[0] == '\0' ||
> strcmp(trace_probe_name(&tu->tp), event) == 0) &&
> (!system || strcmp(trace_probe_group_name(&tu->tp), system) == 0) &&
> --
> 2.7.4

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