Messages in this thread | | | From | David Laight <> | Subject | RE: Re:Re: [PATCH] powerpc: Fix a bug in div64 32 if divisor is zero | Date | Mon, 24 Aug 2020 15:05:13 +0000 |
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From: Guohua Zhong > Sent: 24 August 2020 14:26 > > >> >In generic version in lib/math/div64.c, there is no checking of 'base' > >> >either. > >> >Do we really want to add this check in the powerpc version only ? > >> > >> >The only user of __div64_32() is do_div() in > >> >include/asm-generic/div64.h. Wouldn't it be better to do the check there ? > >> > >> >Christophe > >> > >> Yet, I have noticed that there is no checking of 'base' in these functions. > >> But I am not sure how to check is better.As we know that the result is > >> undefined when divisor is zero. It maybe good to print error and dump stack.
I thought that the onus was put on the caller to avoid divide by zero.
On x86 divide by zero causes an exception which (I'm pretty sure) leads to a oops/panic.
David
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