drbd: Fix five use after free bugs in get_initial_state

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drbd: Fix five use after free bugs in get_initial_state In get_initial_state, it calls notify_initial_state_done(skb,..) if cb->args[5]==1. If genlmsg_put() failed in notify_initial_state_done(), the skb will be freed by nlmsg_free(skb). Then get_initial_state will goto out and the freed skb will be used by return value skb->len, which is a uaf bug. What's worse, the same problem goes even further: skb can also be freed in the notify_*_state_change -> notify_*_state calls below. Thus 4 additional uaf bugs happened. My patch lets the problem callee functions: notify_initial_state_done and notify_*_state_change return an error code if errors happen. So that the error codes could be propagated and the uaf bugs can be avoid. v2 reports a compilation warning. This v3 fixed this warning and built successfully in my local environment with no additional warnings. v2: https://lore.kernel.org/patchwork/patch/1435218/

References

• https://git.kernel.org/stable/c/0489700bfeb1e53eb2039c2291c67e71b0b40103
• https://git.kernel.org/stable/c/dcf6be17b5c53b741898d2223b23e66d682de300
• https://git.kernel.org/stable/c/188fe6b26765edbad4055611c0f788b6870f4024
• https://git.kernel.org/stable/c/b6a4055036eed1f5e239ce3d8b0db1ce38bba447
• https://git.kernel.org/stable/c/594205b4936771a250f9d141e7e0fff21c3dd2d9
• https://git.kernel.org/stable/c/a972c768723359ec995579902473028fe3cd64b1
• https://git.kernel.org/stable/c/de63e74da2333b4068bb79983e632db730fea97e
• https://git.kernel.org/stable/c/226e993c39405292781bfcf4b039a8db56aab362
• https://git.kernel.org/stable/c/aadb22ba2f656581b2f733deb3a467c48cc618f6