netdev - Re: [PATCH net-next 1/2] sfc: fix memory leak on mtd

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Date:   Wed, 11 May 2022 15:03:49 +0200
From:   Íñigo Huguet <ihuguet@...hat.com>
To:     Íñigo Huguet <ihuguet@...hat.com>,
        Edward Cree <ecree.xilinx@...il.com>,
        "David S. Miller" <davem@...emloft.net>, edumazet@...gle.com,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        Liang Li <liali@...hat.com>
Subject: Re: [PATCH net-next 1/2] sfc: fix memory leak on mtd_probe

On Wed, May 11, 2022 at 2:58 PM Martin Habets <habetsm.xilinx@...il.com> wrote:
>
> The same patch was submitted earlier, see
> https://lore.kernel.org/netdev/20220510153619.32464-1-ap420073@gmail.com/

Seriously? It has been there for 9 years and 2 persons find it and
send the fix with hours of difference? Is someone spying me?

Please review the other one and if it's OK, I will send it alone.

>
> Martin
>
> On Wed, May 11, 2022 at 12:36:03PM +0200, Íñigo Huguet wrote:
> > In some cases there is no mtd partitions that can be probed, so the mtd
> > partitions list stays empty. This happens, for example, in SFC9220
> > devices on the second port of the NIC.
> >
> > The memory for the mtd partitions is deallocated in efx_mtd_remove,
> > recovering the address of the first element of efx->mtd_list and then
> > deallocating it. But if the list is empty, the address passed to kfree
> > doesn't point to the memory allocated for the mtd partitions, but to the
> > list head itself. Despite this hasn't caused other problems other than
> > the memory leak, this is obviously incorrect.
> >
> > This patch deallocates the memory during mtd_probe in the case that
> > there are no probed partitions, avoiding the leak.
> >
> > This was detected with kmemleak, output example:
> > unreferenced object 0xffff88819cfa0000 (size 46560):
> >   comm "kworker/0:2", pid 48435, jiffies 4364987018 (age 45.924s)
> >   hex dump (first 32 bytes):
> >     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >   backtrace:
> >     [<000000000f8e92d9>] kmalloc_order_trace+0x19/0x130
> >     [<0000000042a03844>] efx_ef10_mtd_probe+0x12d/0x320 [sfc]
> >     [<000000004555654f>] efx_pci_probe.cold+0x4e1/0x6db [sfc]
> >     [<00000000b03d5126>] local_pci_probe+0xde/0x170
> >     [<00000000376cc8d9>] work_for_cpu_fn+0x51/0xa0
> >     [<00000000141f8de9>] process_one_work+0x8cb/0x1590
> >     [<00000000cb2d8065>] worker_thread+0x707/0x1010
> >     [<000000001ef4b9f6>] kthread+0x364/0x420
> >     [<0000000014767137>] ret_from_fork+0x22/0x30
> >
> > Fixes: 8127d661e77f ("sfc: Add support for Solarflare SFC9100 family")
> > Reported-by: Liang Li <liali@...hat.com>
> > Signed-off-by: Íñigo Huguet <ihuguet@...hat.com>
> > ---
> >  drivers/net/ethernet/sfc/ef10.c        | 5 +++++
> >  drivers/net/ethernet/sfc/siena/siena.c | 5 +++++
> >  2 files changed, 10 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
> > index c9ee5011803f..15a229731296 100644
> > --- a/drivers/net/ethernet/sfc/ef10.c
> > +++ b/drivers/net/ethernet/sfc/ef10.c
> > @@ -3579,6 +3579,11 @@ static int efx_ef10_mtd_probe(struct efx_nic *efx)
> >               n_parts++;
> >       }
> >
> > +     if (n_parts == 0) {
> > +             kfree(parts);
> > +             return 0;
> > +     }
> > +
> >       rc = efx_mtd_add(efx, &parts[0].common, n_parts, sizeof(*parts));
> >  fail:
> >       if (rc)
> > diff --git a/drivers/net/ethernet/sfc/siena/siena.c b/drivers/net/ethernet/sfc/siena/siena.c
> > index 741313aff1d1..32467782e8ef 100644
> > --- a/drivers/net/ethernet/sfc/siena/siena.c
> > +++ b/drivers/net/ethernet/sfc/siena/siena.c
> > @@ -943,6 +943,11 @@ static int siena_mtd_probe(struct efx_nic *efx)
> >               nvram_types >>= 1;
> >       }
> >
> > +     if (n_parts == 0) {
> > +             kfree(parts);
> > +             return 0;
> > +     }
> > +
> >       rc = siena_mtd_get_fw_subtypes(efx, parts, n_parts);
> >       if (rc)
> >               goto fail;
> > --
> > 2.34.1
>


-- 
Íñigo Huguet