traceprobe_expand_meta_args() parses $argN with simple_strtoul() and
calls sprint_nth_btf_arg(n - 1, ...). For $arg0, n is 0 so the index is
-1. Because ctx->nr_params is signed, the "idx >= nr_params" guard in
sprint_nth_btf_arg() does not catch the negative index, and
ctx->params[-1].name_off is read out of bounds.
The normal per-argument path (parse_probe_vars()) already rejects
$arg0 via its argument-number check, but meta-argument expansion runs
before per-argument parsing and substitutes the value first, bypassing
that check.
Reject $arg0 explicitly during expansion.
Fixes: 18b1e870a496 ("tracing/probes: Add $arg* meta argument for all function args")
Signed-off-by: Raushan Patel <raushan.jhon@gmail.com>
---
kernel/trace/trace_probe.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 506e6037e163..c8fd9b946f44 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1901,7 +1901,11 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
trace_probe_log_err(0, BAD_VAR);
return ERR_PTR(-ENOENT);
}
- /* Note: $argN starts from $arg1 */
+ /* Note: $argN starts from $arg1, so $arg0 is invalid. */
+ if (n == 0) {
+ trace_probe_log_err(0, BAD_ARG_NUM);
+ return ERR_PTR(-EINVAL);
+ }
ret = sprint_nth_btf_arg(n - 1, type, buf + used,
bufsize - used, ctx);
if (ret < 0)
--
2.53.0