Messages in this thread | | | Subject | Re: [PATCH v2] powerpc/mpc5xxx: Avoid dereferencing potentially freed memory | From | Christophe JAILLET <> | Date | Fri, 16 Oct 2015 22:05:55 +0200 |
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Le 16/10/2015 11:49, Michael Ellerman a écrit : > On Fri, 2015-10-16 at 08:20 +0200, Christophe JAILLET wrote: >> Le 15/10/2015 08:36, Michael Ellerman a écrit : >>> On Thu, 2015-10-15 at 07:56 +0200, Christophe JAILLET wrote: >>>> Use 'of_property_read_u32()' instead of >>>> 'of_get_property()'+pointer >>>> dereference in order to avoid access to potentially freed memory. >>>> >>>> Use 'of_get_next_parent()' to simplify the while() loop and avoid >>>> the >>>> need of a temp variable. >>>> >>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> >>>> --- >>>> v2: Use of_property_read_u32 instead of of_get_property+pointer >>>> dereference >>>> *** Untested *** >>> Thanks. >>> >>> Can someone with an mpc5xxx test this? >> Hi, >> I don't think it is an issue, but while looking at another similar >> patch, I noticed that the proposed patch adds a call to >> be32_to_cpup() >> (within of_property_read_u32). >> Apparently, powerPC is a BE architecture, so this call should be a no >> -op. >> >> Just wanted to point it out, in case of. > Hi Christoph, > > I'm not sure I follow. > > The device tree is always big endian, but of_property_read_u32() does > the > conversion to CPU endian for you already. That is one of the advantages > of > using it. > > cheers >
Hi, sorry if un-clear.
What I mean is that in the patch related 'powerpc/sysdev/mpc5xxx_clocks.c', there was no call to 'be32_to_cpup'. So in the proposed patch, 'of_property_read_u32' adds it.
While in the patch against 'powerpc/kernel/prom.c', 'be32_to_cpup' was called explicitly. So using 'of_property_read_u32' keep the same logic.
Basically the code from 'mpc5xxx_clocks.c' and from 'prom.c' were written the same way. I found spurious that a call to 'be32_to_cpup' was done in only one case. Maybe, it was a missing in 'mpc5xxx_clocks.c'.
I don't know if it can be an issue or not. I just find it 'strange'.
CJ
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