[rsbac] Random "file not found" errors

Amon Ott ao at rsbac.org
Wed Jun 15 09:55:30 CEST 2005

On Mittwoch 15 Juni 2005 09:37, Oliver Breuer wrote:
> When disabling symlink redirection, both errors disappear.
> I also tested kernel 2.6.9 and 2.6.7, each with rsbac 1.2.3. The 
errors appear with kernel 2.6.9. When running kernel 2.6.7, 
everything seems to be ok.

Ok, thanks for this report. We have a fix in 1.2.5-pre1, which seems 
to run fine, but it is an ugly hack which might explode on our heads 
in a few versions or under heavy load.

The reason for the problem is that newer 2.6 kernels mix up the 
filesystem layers - a string in ext2/ext3 code is used directly via 
pointer instead of copying safely as in previous versions.
The old symlink redirection replaces it with a temporary string, which 
is deallocated afterwards - but gets referenced in the follow_link 
code due to the direct access instead of copying. If the chunk of 
memory gets reused before this access, e.g. because of another 
symlink in the lookup chain, we get the errors.

I am still looking for a better solution. Until then, please keep 
running without symlink redirection.

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