Messages in this thread | | | Date | Wed, 15 May 2024 09:36:36 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC] Mitigating unexpected arithmetic overflow |
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On Wed, May 08, 2024 at 04:47:25PM -0700, Linus Torvalds wrote: > For example, the most common case of overflow we've ever had has very > much been array indexing. Now, sometimes that has actually been actual > undefined behavior, because it's been overflow in signed variables, > and those are "easy" to find in the sense that you just say "no, can't > do that". UBSAN finds them, and that's good.
We build with -fno-strict-overflow, which implies -fwrapv, which removes the UB from signed overflow by mandating 2s complement.
With the exception of an UBSAN bug prior to GCC-8, UBSAN will not, and should not, warn about signed overflow when using either of these flags.
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