Hi!
Le samedi 28 octobre 2023, 02:31:26 EET Andrii Nakryiko a écrit :
> Recent changes to count number of matching symbols when creating
> a kprobe event failed to take into account kernel modules. As such, it
> breaks kprobes on kernel module symbols, by assuming there is no match.
Ah... Sorry about this...
Thank you for the fix, I will handle the patch for older kernels in case there
are troubles applying it.
> Fix this my calling module_kallsyms_on_each_symbol() in addition to
> kallsyms_on_each_match_symbol() to perform a proper counting.
>
> Cc: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func
> matches several symbols") Signed-off-by: Andrii Nakryiko
> <andrii@xxxxxxxxxx>
> ---
> kernel/trace/trace_kprobe.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index effcaede4759..1efb27f35963 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -714,14 +714,30 @@ static int count_symbols(void *data, unsigned long
> unused) return 0;
> }
>
> +struct sym_count_ctx {
> + unsigned int count;
> + const char *name;
> +};
> +
> +static int count_mod_symbols(void *data, const char *name, unsigned long
> unused) +{
> + struct sym_count_ctx *ctx = data;
> +
> + if (strcmp(name, ctx->name) == 0)
> + ctx->count++;
> +
> + return 0;
> +}
> +
> static unsigned int number_of_same_symbols(char *func_name)
> {
> - unsigned int count;
> + struct sym_count_ctx ctx = { .count = 0, .name = func_name };
> +
> + kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
>
> - count = 0;
> - kallsyms_on_each_match_symbol(count_symbols, func_name, &count);
> + module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx);
>
> - return count;
> + return ctx.count;
> }
>
> static int __trace_kprobe_create(int argc, const char *argv[])
Best regards.
