stack overflow bug in ofstream::operator<<
Tue Jun 28 16:06:00 GMT 2005
>From: Corinna Vinschen
>Sent: 28 June 2005 16:57
> I had something like that as a local patch but that's a bit dangerous.
Well, yeh. But somewhat less dangerous than the existing situation!
> Imagine a process using lots of stack space before calling writev and
> there's only, say, 32K left.
Imagine a process using no stack space at all before calling writev and
there's only, say, 2Mb left. Oh, hang on, that's where we came in!
> It would potentially get a SEGV since
> alloca is used while it would still work when using malloc. Of course
> malloc could fail for a process using lots of malloc'ed space. However,
> malloc should at least not SEGV but just return with a NULL pointer...
Indeed, and perhaps the best fix of all would be if alloca was able to
return NULL when there wasn't enough space on the stack.
> So, I guess I'll just check it in using malloc.
Hmm. Can't we tell how much space there is on the stack from the pointers
to the stack limits in the NT_TIB (or whatever lives at %fs on 9x), where we
get the tls pointers from?
Can't think of a witty .sigline today....
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