On Fri, Sep 02, 2022 at 03:41:35AM +0000, Oleksandr Tymoshenko wrote:
release_task, where the seccomp's filter refcounter is released, is not called for the case when the fork/clone is terminated midway by a signal. This leaves an extra reference that prevents filter from being destroyed even after all processes using it exit leading to a BPF JIT memory leak. Dereference the refcounter in the failure path of the copy_process function.
Fixes: 3a15fb6ed92c ("seccomp: release filter after task is fully dead") Cc: Christian Brauner brauner@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Oleksandr Tymoshenko ovt@google.com
Hey Oleksandr,
Thanks for the patch! I'm really puzzled as to why we never noticed this and I'm trying to re-architect how this happend. But in any case, there's a patch in the seccomp tree that fixes this:
https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id=6d...
which is slighly different from your approach in that it moves copy_seccomp() after the point of no return. Let us know if you see any issues with this!
Christian