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Date: Thu, 12 May 2022 08:34:04 +0200 From: Hannes Reinecke <hare@...e.de> To: Serge Semin <Sergey.Semin@...kalelectronics.ru>, Damien Le Moal <damien.lemoal@...nsource.wdc.com>, Hans de Goede <hdegoede@...hat.com>, Jens Axboe <axboe@...nel.dk> Cc: Serge Semin <fancer.lancer@...il.com>, Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>, Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>, Rob Herring <robh+dt@...nel.org>, linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org, devicetree@...r.kernel.org Subject: Re: [PATCH v3 09/23] ata: libahci_platform: Sanity check the DT child nodes number On 5/12/22 01:17, Serge Semin wrote: > Having greater than (AHCI_MAX_PORTS = 32) ports detected isn't that > critical from the further AHCI-platform initialization point of view since > exceeding the ports upper limit will cause allocating more resources than > will be used afterwards. But detecting too many child DT-nodes doesn't > seem right since it's very unlikely to have it on an ordinary platform. In > accordance with the AHCI specification there can't be more than 32 ports > implemented at least due to having the CAP.NP field of 4 bits wide and the > PI register of dword size. Thus if such situation is found the DTB must > have been corrupted and the data read from it shouldn't be reliable. Let's > consider that as an erroneous situation and halt further resources > allocation. > > Note it's logically more correct to have the nports set only after the > initialization value is checked for being sane. So while at it let's make > sure nports is assigned with a correct value. > > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru> > > --- > > Changelog v2: > - Drop the else word from the child_nodes value checking if-else-if > statement (@Damien) and convert the after-else part into the ternary > operator-based statement. > --- > drivers/ata/libahci_platform.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c > index 7ff6626fd569..4e54e19f07b2 100644 > --- a/drivers/ata/libahci_platform.c > +++ b/drivers/ata/libahci_platform.c > @@ -480,15 +480,22 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev, > } > } > > - hpriv->nports = child_nodes = of_get_child_count(dev->of_node); > + /* > + * Too many sub-nodes most likely means having something wrong with > + * the firmware. > + */ > + child_nodes = of_get_child_count(dev->of_node); > + if (child_nodes > AHCI_MAX_PORTS) { > + rc = -EINVAL; > + goto err_out; > + } > > /* > * If no sub-node was found, we still need to set nports to > * one in order to be able to use the > * ahci_platform_[en|dis]able_[phys|regulators] functions. > */ > - if (!child_nodes) > - hpriv->nports = 1; > + hpriv->nports = child_nodes ?: 1; > > hpriv->phys = devm_kcalloc(dev, hpriv->nports, sizeof(*hpriv->phys), GFP_KERNEL); > if (!hpriv->phys) { Reviewed-by: Hannes Reinecke <hare@...e.de> Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@...e.de +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
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