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    Subject[PATCH AUTOSEL 4.20 298/304] proc/sysctl: fix return error for proc_doulongvec_minmax()
    Date
    From: Cheng Lin <cheng.lin130@zte.com.cn>

    [ Upstream commit 09be178400829dddc1189b50a7888495dd26aa84 ]

    If the number of input parameters is less than the total parameters, an
    EINVAL error will be returned.

    For example, we use proc_doulongvec_minmax to pass up to two parameters
    with kern_table:

    {
    .procname = "monitor_signals",
    .data = &monitor_sigs,
    .maxlen = 2*sizeof(unsigned long),
    .mode = 0644,
    .proc_handler = proc_doulongvec_minmax,
    },

    Reproduce:

    When passing two parameters, it's work normal. But passing only one
    parameter, an error "Invalid argument"(EINVAL) is returned.

    [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals
    [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
    1 2
    [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals
    -bash: echo: write error: Invalid argument
    [root@cl150 ~]# echo $?
    1
    [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
    3 2
    [root@cl150 ~]#

    The following is the result after apply this patch. No error is
    returned when the number of input parameters is less than the total
    parameters.

    [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals
    [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
    1 2
    [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals
    [root@cl150 ~]# echo $?
    0
    [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
    3 2
    [root@cl150 ~]#

    There are three processing functions dealing with digital parameters,
    __do_proc_dointvec/__do_proc_douintvec/__do_proc_doulongvec_minmax.

    This patch deals with __do_proc_doulongvec_minmax, just as
    __do_proc_dointvec does, adding a check for parameters 'left'. In
    __do_proc_douintvec, its code implementation explicitly does not support
    multiple inputs.

    static int __do_proc_douintvec(...){
    ...
    /*
    * Arrays are not supported, keep this simple. *Do not* add
    * support for them.
    */
    if (vleft != 1) {
    *lenp = 0;
    return -EINVAL;
    }
    ...
    }

    So, just __do_proc_doulongvec_minmax has the problem. And most use of
    proc_doulongvec_minmax/proc_doulongvec_ms_jiffies_minmax just have one
    parameter.

    Link: http://lkml.kernel.org/r/1544081775-15720-1-git-send-email-cheng.lin130@zte.com.cn
    Signed-off-by: Cheng Lin <cheng.lin130@zte.com.cn>
    Acked-by: Luis Chamberlain <mcgrof@kernel.org>
    Reviewed-by: Kees Cook <keescook@chromium.org>
    Cc: Alexey Dobriyan <adobriyan@gmail.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/sysctl.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/kernel/sysctl.c b/kernel/sysctl.c
    index 5fc724e4e454..9ee261fce89e 100644
    --- a/kernel/sysctl.c
    +++ b/kernel/sysctl.c
    @@ -2779,6 +2779,8 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
    bool neg;

    left -= proc_skip_spaces(&p);
    + if (!left)
    + break;

    err = proc_get_long(&p, &left, &val, &neg,
    proc_wspace_sep,
    --
    2.19.1
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