[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.
Amon.
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