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Subject[for-next][PATCH 06/13] tracing: probeevent: Fix to make the type of $comm string
From: Masami Hiramatsu <mhiramat@kernel.org>

Fix to make the type of $comm "string". If we set the other type to $comm
argument, it shows meaningless value or wrong data. Currently probe events
allow us to set string array type (e.g. ":string[2]"), or other digit types
like x8 on $comm. But since clearly $comm is just a string data, it should
not be fetched by other types including array.

Link: http://lkml.kernel.org/r/155723736241.9149.14582064184468574539.stgit@devnote2

Cc: Andreas Ziegler <andreas.ziegler@fau.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_probe.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4cc2d467d34c..e0d1d5353464 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -533,13 +533,14 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
}
}
}
- /*
- * The default type of $comm should be "string", and it can't be
- * dereferenced.
- */
- if (!t && strcmp(arg, "$comm") == 0)
+
+ /* Since $comm can not be dereferred, we can find $comm by strcmp */
+ if (strcmp(arg, "$comm") == 0) {
+ /* The type of $comm must be "string", and not an array. */
+ if (parg->count || (t && strcmp(t, "string")))
+ return -EINVAL;
parg->type = find_fetch_type("string");
- else
+ } else
parg->type = find_fetch_type(t);
if (!parg->type) {
trace_probe_log_err(offset + (t ? (t - arg) : 0), BAD_TYPE);
--
2.20.1

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