Messages in this thread | | | Subject | Re: [PATCH] hw_random: free rng_buffer at module exit | From | Ben Hutchings <> | Date | Sun, 17 Mar 2013 02:14:52 +0000 |
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On Fri, 2013-03-15 at 15:35 +1030, Rusty Russell wrote: > Satoru Takeuchi <satoru.takeuchi@gmail.com> writes: > > At Thu, 14 Mar 2013 17:11:21 +1030, > > Rusty Russell wrote: > >> > >> Satoru Takeuchi <satoru.takeuchi@gmail.com> writes: > >> > Hi Rusty, > >> > > >> > At Tue, 12 Mar 2013 15:43:33 -0700, > >> > Greg Kroah-Hartman wrote: > >> >> @@ -307,6 +312,14 @@ int hwrng_register(struct hwrng *rng) > >> >> > >> >> mutex_lock(&rng_mutex); > >> >> > >> >> + /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ > >> >> + err = -ENOMEM; > >> >> + if (!rng_buffer) { > >> >> + rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); > >> > > >> > rng_buffer is now kmalloc-ed, but not kfree-ed. Shoudn't it be kfree-ed > >> > at hwrng_unregister()? If my suspect is correct, the same problem is > >> > in 3.8.3-rc1 and 3.0.69-rc1. I'm OK to make a patch, but it'll be after > >> > some hours. > >> > > >> > Corecct me if I'm wrong. > >> > >> Yes, it would be nice to free it, but it really makes sense to free it > >> in module_cleanup() (which would have to be written, as the module > >> currently doesn't have one). > >> > >> Cheers, > >> Rusty. > > > > From: Satoru Takeuchi <satoru.takeuchi@gmail.com> > > > > rng-core module allocates rng_buffer by kmalloc() since commit > > f7f154f1246ccc5a0a7e9ce50932627d60a0c878. But this buffer won't be > > freed and there is a memory leak possibility at module exit. > > > > Signed-off-by: Satoru Takeuchi <satoru.takeuchi@gmail.com> > > Cc: Rusty Russell <rusty@rustcorp.com.au> > > Cc: Matt Mackall <mpm@selenic.com> > > Cc: Herbert Xu <herbert@gondor.apana.org.au> > > Cc: Aurelien Jarno <aurelien@aurel32.net> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: stable@vger.kernel.org > > Cc: stable might be overkill, but I've tested it and put it in my patch > queue, and will push it to Linus once it's survived linux-next.
If the module cannot be removed currently, it does not leak. Making it removable is a feature addition and I think you're right that it's not suitable for stable.
Ben.
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