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    Subject[PATCH 5.0 11/89] tracing: Fix a memory leak by early error exit in trace_pid_write()
    Date
    From: Wenwen Wang <wang6495@umn.edu>

    commit 91862cc7867bba4ee5c8fcf0ca2f1d30427b6129 upstream.

    In trace_pid_write(), the buffer for trace parser is allocated through
    kmalloc() in trace_parser_get_init(). Later on, after the buffer is used,
    it is then freed through kfree() in trace_parser_put(). However, it is
    possible that trace_pid_write() is terminated due to unexpected errors,
    e.g., ENOMEM. In that case, the allocated buffer will not be freed, which
    is a memory leak bug.

    To fix this issue, free the allocated buffer when an error is encountered.

    Link: http://lkml.kernel.org/r/1555726979-15633-1-git-send-email-wang6495@umn.edu

    Fixes: f4d34a87e9c10 ("tracing: Use pid bitmap instead of a pid array for set_event_pid")
    Cc: stable@vger.kernel.org
    Signed-off-by: Wenwen Wang <wang6495@umn.edu>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/trace/trace.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    --- a/kernel/trace/trace.c
    +++ b/kernel/trace/trace.c
    @@ -496,8 +496,10 @@ int trace_pid_write(struct trace_pid_lis
    * not modified.
    */
    pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
    - if (!pid_list)
    + if (!pid_list) {
    + trace_parser_put(&parser);
    return -ENOMEM;
    + }

    pid_list->pid_max = READ_ONCE(pid_max);

    @@ -507,6 +509,7 @@ int trace_pid_write(struct trace_pid_lis

    pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
    if (!pid_list->pids) {
    + trace_parser_put(&parser);
    kfree(pid_list);
    return -ENOMEM;
    }

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