Messages in this thread | | | Subject | Re: I discussed reading directories as files with jra, Stallman, | Date | Mon, 21 Jun 1999 11:18:11 +0100 (BST) | From | Alan Cox <> |
| |
> and that's what happens here. It's not the fact that we have a recursive > lookup_dentry(), it's bringing tons of cruft into stack between the nested > calls and severe code duplication. And multiple pathes of recursion (every > foo_follow_link contains one).
The fact we have fs recursion is actually bad, but purely because we don't have dynamic stack allocation. (Which we dont want either). With a non recudsive follow link we could probably go back to 4K stacks. If thats the case then on x86 recursive link following currently costs us 4K a process idle, or otherwise. Ie about 350K of unswappable memory on my box currently.
> It's order of magnitude. I'm more than sure that with sufficiently long > and perverted code path (we have them) the current implementation can be > used to overflow the ring 0 stack.
Try a self referencing symlink on smbfs - although that appears to be not entirely the VFS fault.
> PS: ObCodeDuplication: sys_mmap() on PPC. down(¤t->mm->mmap_sem) > missing. fcheck() instead of fget(). The former is more or less fresh, but > the latter is about 1.5 years old. Exploitable race. Sigh... And there are > other similar buggers. grep(1) is our friend...
patch ?
Alan
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |