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    Subject[PATCH AUTOSEL 5.1 058/186] tracing: probeevent: Fix to make the type of $comm string
    Date
    From: Masami Hiramatsu <mhiramat@kernel.org>

    [ Upstream commit 3dd1f7f24f8ceec00bbbc364c2ac3c893f0fdc4c ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.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 8f8411e7835fd..e41d389b7f491 100644
    --- a/kernel/trace/trace_probe.c
    +++ b/kernel/trace/trace_probe.c
    @@ -420,13 +420,14 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
    return -E2BIG;
    }
    }
    - /*
    - * 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) {
    pr_info("Unsupported type: %s\n", t);
    --
    2.20.1
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