arm64: ftrace: fix module PLTs with mcount
Summary
arm64: ftrace: fix module PLTs with mcount
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
arm64: ftrace: fix module PLTs with mcount
Li Huafei reports that mcount-based ftrace with module PLTs was broken
by commit:
a6253579977e4c6f ("arm64: ftrace: consistently handle PLTs.")
When a module PLTs are used and a module is loaded sufficiently far away
from the kernel, we'll create PLTs for any branches which are
out-of-range. These are separate from the special ftrace trampoline
PLTs, which the module PLT code doesn't directly manipulate.
When mcount is in use this is a problem, as each mcount callsite in a
module will be initialized to point to a module PLT, but since commit
a6253579977e4c6f ftrace_make_nop() will assume that the callsite has
been initialized to point to the special ftrace trampoline PLT, and
ftrace_find_callable_addr() rejects other cases.
This means that when ftrace tries to initialize a callsite via
ftrace_make_nop(), the call to ftrace_find_callable_addr() will find
that the _mcount stub is out-of-range and is not handled by the ftrace
PLT, resulting in a splat:
| ftrace_test: loading out-of-tree module taints kernel.
| ftrace: no module PLT for _mcount
| ------------[ ftrace bug ]------------
| ftrace failed to modify
| [] 0xffff800029180014
| actual: 44:00:00:94
| Initializing ftrace call sites
| ftrace record flags: 2000000
| (0)
| expected tramp: ffff80000802eb3c
| ------------[ cut here ]------------
| WARNING: CPU: 3 PID: 157 at kernel/trace/ftrace.c:2120 ft…
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2022-50579 linux Fixed in: 5.10.158-1
- Ubuntu UBUNTU-CVE-2022-50579 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org