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 <ja...@zx2c4.com>
Reviewed-by: Johannes Berg <johan...@sipsolutions.net>
FWIW, I found another (indirect, via genetlink, like ila_xlat.c) in-
tree user that cares and expects the correct failure behaviour:
net/ipv6/seg6.c
.start = seg6_genl_dumphmac_start,
which can also have memory allocation failures. No others appear to
exist, afaict.
Either way, perhaps it's worth sending this to stable for that reason.
johannes
