Re: [PATCH] powerpc/ipic: Fix a bounds check in ipic_set_priority()

Le 05/12/2018 à 04:26, Michael Ellerman a écrit :

Hi Dan,

Thanks for the patch.

Dan Carpenter [off-list ref] writes:

quoted

The ipic_info[] array only has 95 elements so I have made the bounds
check smaller to prevent a read overflow.  It was Smatch that found
this issue:

     arch/powerpc/sysdev/ipic.c:784 ipic_set_priority()
     error: buffer overflow 'ipic_info' 95 <= 127

Signed-off-by: Dan Carpenter <redacted>
---
I wasn't able to find any callers of this code.  Maybe we removed the
last one in commit b9f0f1bb2bca ("[POWERPC] Adapt ipic driver to new
host_ops interface, add set_irq_type to set IRQ sense").  So perhaps we
should just remove it.  I'm not really comfortable doing that myself,
because I don't know the code well enough and can't build test
it properly.

Hah wow, last usage removed in 2006!

I don't see any mention of it since then, so I'll remove it. If it
breaks something we can put it back.

Can smatch help us find things like this that are defined non-static but
never used?

I think we have to do that carrefully. Some of those functions might be 
used by out-of-tree boards.

I'm thinking especially at ipic_get_mcp_status() and 
ipic_set_mcp_status(). They are used in my 832x boards's machine check 
handler to know when a machine check is a timeout from the 832x watchdog.

Christophe