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SubjectRe: [PATCH] ftrace: fix function type mismatches
On Mon, Oct 07, 2019 at 02:47:40PM -0700, Sami Tolvanen wrote:
> This change fixes indirect call mismatches with function and function
> graph tracing, which trip Control-Flow Integrity (CFI) checking.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Thanks for sending this! We're getting pretty close to having all the
various CFI issues cleaned up now. :)

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
> kernel/trace/fgraph.c | 9 ++++++---
> kernel/trace/ftrace.c | 8 +++++---
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 7950a0356042..ecfd4a4a106a 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -327,14 +327,17 @@ void ftrace_graph_sleep_time_control(bool enable)
> fgraph_sleep_time = enable;
> }
>
> +void ftrace_graph_return_stub(struct ftrace_graph_ret *trace)
> +{
> +}
> +
> int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
> {
> return 0;
> }
>
> /* The callbacks that hook a function */
> -trace_func_graph_ret_t ftrace_graph_return =
> - (trace_func_graph_ret_t)ftrace_stub;
> +trace_func_graph_ret_t ftrace_graph_return = ftrace_graph_return_stub;
> trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
> static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
>
> @@ -614,7 +617,7 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
> goto out;
>
> ftrace_graph_active--;
> - ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
> + ftrace_graph_return = ftrace_graph_return_stub;
> ftrace_graph_entry = ftrace_graph_entry_stub;
> __ftrace_graph_entry = ftrace_graph_entry_stub;
> ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 62a50bf399d6..b68ee130d4a2 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -125,8 +125,9 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *op, struct pt_regs *regs);
> #else
> /* See comment below, where ftrace_ops_list_func is defined */
> -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
> -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
> +static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip,
> + struct ftrace_ops *op, struct pt_regs *regs);
> +#define ftrace_ops_list_func ftrace_ops_no_ops
> #endif
>
> static inline void ftrace_ops_init(struct ftrace_ops *ops)
> @@ -6325,7 +6326,8 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> }
> NOKPROBE_SYMBOL(ftrace_ops_list_func);
> #else
> -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
> +static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip,
> + struct ftrace_ops *op, struct pt_regs *regs)
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
> }
> --
> 2.23.0.581.g78d2f28ef7-goog
>

--
Kees Cook

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