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Well. I'll gladly admit that the C code I have written was way less complex than a web browser. When I still wrote C code for a living, I worked on an applicati

by krylon 11y ago

Well. I'll gladly admit that the C code I have written was way less complex than a web browser. When I still wrote C code for a living, I worked on an application suite that was ~250k lines of code, maybe ~300k, in total, whereas e.g. Firefox is a couple of million lines. I assume other mainstream browsers are similarly big. Plus, what a browser does is, by nature, a lot more complicated than what I worked on. EDIT: What I am trying to say is: I do not mean to trivialize use-after-free bugs, but in my personal experience, I did not run into many, while I witnessed (and caused, I am afraid) a bunch of array bounds violations, and they sometimes made me want to cry.

eru 11y ago
Yeah, browsers are essentially interpreters (and nowadays compilers) for a variety of crazy languages (html, css, javascript; probably a few more?). You don't want to be writing your interpreters in C.
- krylon 11y ago
  > You don't want to be writing your interpreters in C. Well, technically, I think most browsers these days are written in C++, but your point remains valid. OTOH, the "default" Python interpreter is written in C, and so is Perl (Ruby MRI, too, I think, but I am not 100% certain). I cannot recall any major security problem with those languages that originated inside the interpreter (which, of course, does not mean those did not/do not exist). Then again, a web browser is probably far messier in terms of what input is has to deal with.
  - masklinn 11y ago
    > Then again, a web browser is probably far messier in terms of what input is has to deal with. That's the ticket, the browser does have a large attack surface but more importantly it's supposed to safely execute completely arbitrary and untrusted payloads. In the same category are pretty much all of the usual suspect of security issues: flash, java (applets), … Most interpreters are only fed trusted payloads, lest the developer starts eval'ing stuff they got from god knows where, and in that case the fault is usually laid to the developer's feet rather than the interpreter's.
    - eru 11y ago
      Yeah. The browser is more like a hypervizor that Amazon might be running to run arbitrary people's VMs. But it has an unimaginably larger surface area than Xen.

by krylon 11y ago

eru 11y ago

Yeah, browsers are essentially interpreters (and nowadays compilers) for a variety of crazy languages (html, css, javascript; probably a few more?). You don't want to be writing your interpreters in C.

krylon 11y ago
> You don't want to be writing your interpreters in C. Well, technically, I think most browsers these days are written in C++, but your point remains valid. OTOH, the "default" Python interpreter is written in C, and so is Perl (Ruby MRI, too, I think, but I am not 100% certain). I cannot recall any major security problem with those languages that originated inside the interpreter (which, of course, does not mean those did not/do not exist). Then again, a web browser is probably far messier in terms of what input is has to deal with.
- masklinn 11y ago
  > Then again, a web browser is probably far messier in terms of what input is has to deal with. That's the ticket, the browser does have a large attack surface but more importantly it's supposed to safely execute completely arbitrary and untrusted payloads. In the same category are pretty much all of the usual suspect of security issues: flash, java (applets), … Most interpreters are only fed trusted payloads, lest the developer starts eval'ing stuff they got from god knows where, and in that case the fault is usually laid to the developer's feet rather than the interpreter's.
  - eru 11y ago
    Yeah. The browser is more like a hypervizor that Amazon might be running to run arbitrary people's VMs. But it has an unimaginably larger surface area than Xen.