Re: [PATCH v2] netlink: do not proceed if dump's start() errs

[David Miller]

From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Date: Sat, 30 Sep 2017 08:56:10 +0200

> On Thu, 2017-09-28 at 00:41 +0200, Jason A. Donenfeld wrote:
>> Drivers that use the start method for netlink dumping rely on dumpit
>> not
>> being called if start fails. For example, ila_xlat.c allocates memory
>> and assigns it to cb->args[0] in its start() function. It might fail
>> to
>> do that and return -ENOMEM instead. However, even when returning an
>> error, dumpit will be called, which, in the example above, quickly
>> dereferences the memory in cb->args[0], which will OOPS the kernel.
>> This
>> is but one example of how this goes wrong.
>> 
>> Since start() has always been a function with an int return type, it
>> therefore makes sense to use it properly, rather than ignoring it.
>> This
>> patch thus returns early and does not call dumpit() when start()
>> fails.
>> 
>> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> 
> Reviewed-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
 ...
> Either way, perhaps it's worth sending this to stable for that reason.

Agreed, applied and queued up for -stable, thanks.