c326c0a7df
Bugzilla: https://bugzilla.redhat.com/2104750 CVE: CVE-2022-21499 Description: KDB and KGDB must be appropriately restricted when kernel lockdown is in effect. This is pertinent to RHEL since the kernel CONFIG options that enable KDB and KGDB support are selected for both the normal and debug RHEL kernels. Upstream Status: eadb2f47a3ced5c64b23b90fd2a3463f63726066 Tested: Verified that when UEFI Secure Boot is enabled, writes to memory in kdb fail with a permission error and any entry into kgdb is blocked. commit eadb2f47a3ced5c64b23b90fd2a3463f63726066 Author: Daniel Thompson <daniel.thompson@linaro.org> Date: Mon May 23 19:11:02 2022 +0100 lockdown: also lock down previous kgdb use KGDB and KDB allow read and write access to kernel memory, and thus should be restricted during lockdown. An attacker with access to a serial port (for example, via a hypervisor console, which some cloud vendors provide over the network) could trigger the debugger so it is important that the debugger respect the lockdown mode when/if it is triggered. Fix this by integrating lockdown into kdb's existing permissions mechanism. Unfortunately kgdb does not have any permissions mechanism (although it certainly could be added later) so, for now, kgdb is simply and brutally disabled by immediately exiting the gdb stub without taking any action. For lockdowns established early in the boot (e.g. the normal case) then this should be fine but on systems where kgdb has set breakpoints before the lockdown is enacted than "bad things" will happen. CVE: CVE-2022-21499 Co-developed-by: Stephen Brennan <stephen.s.brennan@oracle.com> Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com> |
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| kdb | ||
| Makefile | ||
| debug_core.c | ||
| debug_core.h | ||
| gdbstub.c | ||