Also, gcc once maintained "fat" pointer to store length of array for bound checking but removed later due to sanitizers such as valgrind.
https://gcc.gnu.org/wiki/MIRO?action=AttachFile&do=get&target=MIRO.pdf There are bounded for loops being discussed in new programming languages for data plane. A bounded for loop is "for ( i < k)" where length of vector is stored in type so that the compiler can unroll loop and verify bound. Hemant -----Original Message----- From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of hemant via lists.fd.io Sent: Wednesday, December 14, 2022 9:00 AM To: vpp-dev@lists.fd.io Subject: Re: [vpp-dev] vpp core & bound checking Hi Ben, What kind of bound failure is causing crashes? Is a for loop terminator exceeding bound or networking data exceeding bound? I can investigate changing the gcc compiler to check any bound at compile-time. Hemant -----Original Message----- From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Benoit Ganne (bganne) via lists.fd.io Sent: Wednesday, November 30, 2022 9:30 AM To: vpp-dev@lists.fd.io Subject: [vpp-dev] vpp core & bound checking Hi everyone, I'd like to get the discussion started on the topic of bound checking in VPP: some of us recently discussed a patch that added explicit bound checking within VPP core dataplane infrastructure to prevent a crash when the function is misused from a plugin. The bug is clearly in the plugin which calls the VPP infra function, but it's a hard one to track and when it happens it crashes VPP and break networking for users. I think we do not want to do bound checking in the core VPP dataplane infra for performance reasons, and hence callers should be correct or nasty things will happen. In case a workaround is really needed, it should be done in the caller and probably maintained as a private patch until the bug is properly fixed. What do people think? Best ben
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