21–30 of 31 posts
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Ada is a modern language that allows for very low level code and is about as fast as C.
Thats what the US military use on mission critical systems, right? Seem to recall reading that it is a pain to work with.
From FOSDEM talks its use has been increasing thanks to C lack of safety, even with MISRA C.
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The idea of passing around function pointers like raw values that way, or having a language+runtime without array bounds checks or checks for dereferencing invalid pointers is just frightening. We have tools now such that if they had been around in the 60's/70's we wouldn't have these problems. So why not start rebuilding low level systems using better tools? Granted, if we rewrite kernels, drivers, encryption etc in…
> We have tools now such that if they had been around in the 60's/70's we wouldn't have these problems Not for kernel development we don't. The only modern, memory-safe language that gets close(-ish) to the performance of C for kernel development is Rust and it's a long way from being stable enough for mainstream kernel development. And even a safe language like Rust won't prevent escalation problems like this if you…
Earlier quoted context omitted.
The idea of passing around function pointers like raw values that way, or having a language+runtime without array bounds checks or checks for dereferencing invalid pointers is just frightening. We have tools now such that if they had been around in the 60's/70's we wouldn't have these problems. So why not start rebuilding low level systems using better tools? Granted, if we rewrite kernels, drivers, encryption etc in…
Because UNIX was embraced by the enterprise and brought C along. Algol 68, Modula-2, Mesa, Cedar were all options back when UNIX was being brought to life.
Earlier quoted context omitted.
Thats what the US military use on mission critical systems, right? Seem to recall reading that it is a pain to work with.
Ada is used in environments were human lifes are at risk life like life support systems, traffic control and so on. From FOSDEM talks its use has been increasing thanks to C lack of safety, even with MISRA C.
Earlier quoted context omitted.
> We have tools now such that if they had been around in the 60's/70's we wouldn't have these problems Not for kernel development we don't. The only modern, memory-safe language that gets close(-ish) to the performance of C for kernel development is Rust and it's a long way from being stable enough for mainstream kernel development. And even a safe language like Rust won't prevent escalation problems like this if you…
Yes we have. Xerox PARC systems were mainly developed in Mesa after some bootstrap work in BCPL. ETHZ OS were done in Modula-2, Oberon, Active Oberon. Olivetti and DEC were using Modula-3. Several OS were being done in Algol and PL/I dialects back when UNIX was being born. C's ubiquity is a consequence of UNIX adoption by some successful startups in the workstation market. If one of the other systems had enjoyed a si…
Great article! ... I'm glad I already disable hardware acceleration having hit kernel panics there on OS X before. (I did a write up, http://www.brendangregg.com/blog/2014-05-23/osx-10.9.3-is-to... , but it's much less interesting/useful than this blog post).
This writeup, and the first part of this series, are amazing and incredibly instructive. But they make me embarrassed that anyone still runs or writes code that is so without memory safety that these bugs can exist.
Earlier quoted context omitted.
> We have tools now such that if they had been around in the 60's/70's we wouldn't have these problems Not for kernel development we don't. The only modern, memory-safe language that gets close(-ish) to the performance of C for kernel development is Rust and it's a long way from being stable enough for mainstream kernel development. And even a safe language like Rust won't prevent escalation problems like this if you…
The thing is; Rust could have been implemented long ago. It was triggered by Mozillas need for a parallell browser engine that is safe and doesn't crash all the time. One would have thought the same need would have existed for other code such as kernels and drivers for many years.
This writeup, and the first part of this series, are amazing and incredibly instructive. But they make me embarrassed that anyone still runs or writes code that is so without memory safety that these bugs can exist.
What do you expect? Something (language) at some level needs to have physical access to the physical memory.
You'll get no argument from me that a language needs direct access to memory. My problem is that the difference between correct code and exploitable code is extreme diligence on the part of the programmer, which fails constantly. [Arguably static analysis type tools can help a lot, but, that's just trying to recover from an already bad situation.]
For example, in the prequel to the OP's article (http://googleprojectzero.blogspot.com/2014/07/pwn4fun-spring...), the original bug was overflowing an unsigned int. You should be spitting out your coffee! (/beverage of choice) How can it be be that a (presumably expert) programmer can write code that silently overflows integers by accident?
"It's 2014 and this still happens." That's my favorite non-argument. It's not constructive but it expresses how I feel. We're well past the years where people have had time to reflect on the fact that people have already struggled with and tried to solve the problem that this should simply not be possible. I don't need a fancy type system to enforce 'checked integers' are the only things that are passed to to my memcpys - but I do have to be willing, at some point, to discard the broken versions of the same thing I've been holding on to for 30 years in favor of something less perilous.
Oh, and, if you read the rest of that prequel article, the person who fixed the bug missed something else in doing so. They're adding overflow-safe versions of 'size_t' and 'unsigned int' together. Again, embarrassing. Not for their error, but because we-as-a-species are still writing code where that mistake can be made, and then not doing anything about it when it inevitably happens.
Earlier quoted context omitted.
What do you expect? Something (language) at some level needs to have physical access to the physical memory.
(rant ahead) What do I expect? I would expect engineers to identify how awful this situation is years ago and build a replacement. Finally, in the last few years, there are some serious attempts at doing so (Rust comes to mind). But it's taken this long and that astounds me. You'll get no argument from me that a language needs direct access to memory. My problem is that the difference between correct code and exploit…
As I was implementing a dynamic array (vector) last night in C, I thought about the vector_get method that would implemented. It would first check the bounds that it receives as the second arguments (first is struct vector_t instance), and it would only return if that index is less than the current size of the vector. If the bounds is out of reach, the program aborts.
This was a great example of abstraction in C that I found really enjoyable to write.