On Sat, Jan 16, 2016 at 11:05 AM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> Hi Luis,
>
> On Fri, Jan 15, 2016 at 03:42:17PM -0800, Luis R. Rodriguez wrote:
>> From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
>>
>> Commit f2411da746985 ("driver-core: add driver module
>> asynchronous probe support") added async probe support,
>> in two forms:
>>
>> * in-kernel driver specification annotation
>> * generic async_probe module parameter (modprobe foo async_probe)
>>
>> To support the generic kernel parameter parse_args() was
>> extended via commit ecc8617053e0 ("module: add extra
>> argument for parse_params() callback") however commit
>> failed to f2411da746985 failed to add the required argument.
>>
>> This causes a crash then whenever async_probe generic
>> module parameter is used. This was overlooked when the
>> form in which in-kernel async probe support was reworked
>> a bit... Fix this as originally intended.
>>
>> Cc: Hannes Reinecke <hare@xxxxxxx>
>> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx (4.2+)
>> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
>> ---
>>
>> Resending and addressing Rusty, the other patch I sent on Dec 19
>> was addressed to Greg by mistake. Sorry about that.
>>
>> kernel/module.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/module.c b/kernel/module.c
>> index 8f051a106676..88100ea77c55 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -3402,16 +3402,22 @@ out:
>> static int unknown_module_param_cb(char *param, char *val, const char *modname,
>> void *arg)
>> {
>> - struct module *mod = arg;
>> + struct module *mod;
>> int ret;
>>
>> if (strcmp(param, "async_probe") == 0) {
>> + mod = arg;
>> + if (!mod) {
>> + ret = -ENOENT;
>> + goto out;
>> + }
>
> Why do we need this chunk? We only call unknown_module_param_cb() from
> one place and with your chunk below we do know that "mod" is never NULL.
To prevent future bugs that might use this incorrectly.
>> mod->async_probe_requested = true;
>> return 0;
>> }
>>
>> /* Check for magic 'dyndbg' arg */
>> ret = ddebug_dyndbg_module_param_cb(param, val, modname);
>> +out:
>> if (ret != 0)
>> pr_warn("%s: unknown parameter '%s' ignored\n", modname, param);
>> return 0;
>> @@ -3515,7 +3521,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
>>
>> /* Module is ready to execute: parsing args may do that. */
>> after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
>> - -32768, 32767, NULL,
>> + -32768, 32767, mod,
>
> I believe this is the only change that is needed.
For the fix yes, that is true. We could split this in two. Up to Rusty.
Luis
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html