linux-kernel - RE: [PATCH] net: stmmac: add sanity check to device_property_read_u32

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Date:   Wed, 19 Jun 2019 07:13:08 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     colin.king@...onical.com
Cc:     alexandre.torgue@...com, davem@...emloft.net, joabreu@...opsys.com,
        kernel-janitors@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        mcoquelin.stm32@...il.com, netdev@...r.kernel.org,
        peppe.cavallaro@...com
Subject: RE: [PATCH] net: stmmac: add sanity check to device_property_read_u32_array call

Hi Colin,

> Currently the call to device_property_read_u32_array is not error checked
> leading to potential garbage values in the delays array that are then used
> in msleep delays.  Add a sanity check to the property fetching.
> 
> Addresses-Coverity: ("Uninitialized scalar variable")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
I have also sent a patch [0] to fix initialize the array.
can you please look at my patch so we can work out which one to use?

my concern is that the "snps,reset-delays-us" property is optional,
the current dt-bindings documentation states that it's a required
property. in reality it isn't, there are boards (two examples are
mentioned in my patch: [0]) without it.

so I believe that the resulting behavior has to be:
1. don't delay if this property is missing (instead of delaying for
   <garbage value> ms)
2. don't error out if this property is missing

your patch covers #1, can you please check whether #2 is also covered?
I tested case #2 when submitting my patch and it worked fine (even
though I could not reproduce the garbage values which are being read
on some boards)

Thank you!
Martin

[0] https://lkml.org/lkml/2019/4/19/638