tree 7734bd75b1b95c22457c0671c6d9968b131fb5b1
parent fec8898d86ad0fb4d2161fc89885fa52da1e8b72
author Anton Arapov <anton@redhat.com> 1365004837 +0200
committer Oleg Nesterov <oleg@redhat.com> 1365859918 +0200

uretprobes: Limit the depth of return probe nestedness

Unlike the kretprobes we can't trust userspace, thus must have
protection from user space attacks. User-space have  "unlimited"
stack, and this patch limits the return probes nestedness as a
simple remedy for it.

Note that this implementation leaks return_instance on siglongjmp
until exit()/exec().

The intention is to have KISS and bare minimum solution for the
initial implementation in order to not complicate the uretprobes
code.

In the future we may come up with more sophisticated solution that
remove this depth limitation. It is not easy task and lays beyond
this patchset.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>