[OE-core][PATCH v3 6/9] cve-exclusions: set status for CVE-2022-4543

[Junjie Cao <junjie.cao@linux.dev>]

KPTI clones the kernel entry text into the user page tables at its
KASLR-slid address and, on CPUs with PGE, sets the global bit on those
PTEs. The mapping survives the CR3 write on kernel exit, and a local
attacker can time prefetch instructions across the kernel range to
recover the KASLR base in well under a second.

Disclosure and write-up:

  https://www.openwall.com/lists/oss-security/2022/12/16/3
  https://www.willsroot.io/2022/12/entrybleed.html

The disclosure states that after discussion with security@kernel.org and
linux-distros "a fix for this is currently not available", and none has
appeared since; arch/x86/mm/pti.c still clones the entry text and sets
_PAGE_GLOBAL on the cloned PTEs. This is an unfixed issue, not a stated
wontfix - Debian notes "Ignored upstream and KASLR is not expected to be
resistant to local attacks", Ubuntu has it deferred since 2023-01-10:

  https://security-tracker.debian.org/tracker/CVE-2022-4543
  https://ubuntu.com/security/CVE-2022-4543

97e3d26b5e5f ("x86/mm: Randomize per-cpu entry area", v6.2) randomizes
the separate cpu_entry_area; it predates this disclosure and does not
change the offset of entry_SYSCALL_64 from the KASLR base.

CC: Paul Barker <paul@pbarker.dev>
AI-Generated: Uses Claude (claude-opus-5)
Signed-off-by: Junjie Cao <junjie.cao@linux.dev>
---
v3:
- use "unpatched" instead of "upstream-wontfix": the security-team
  discussion produced no clear wontfix decision

v2: https://lore.kernel.org/openembedded-core/20260803084827.1348810-1-junjie.cao@linux.dev/

 meta/recipes-kernel/linux/cve-exclusion.inc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/meta/recipes-kernel/linux/cve-exclusion.inc b/meta/recipes-kernel/linux/cve-exclusion.inc
index b08eaa1..a909aef 100644
--- a/meta/recipes-kernel/linux/cve-exclusion.inc
+++ b/meta/recipes-kernel/linux/cve-exclusion.inc
@@ -229,3 +229,11 @@ was never substantiated and was closed as not-a-bug by Red Hat, SUSE and Debian"
 # Fix https://git.kernel.org/linus/d860d1faa6b2ce3becfdb8b0c2b048ad31800061
 # Fix https://git.kernel.org/linus/da9c9c877597170b929a6121a68dcd3dd9a80f45
 CVE_STATUS[CVE-2022-1247] = "fixed-version: Fixed from version 6.17"
+
+# "EntryBleed": KPTI maps the entry text into the user page tables with
+# the global bit set, leaking the KASLR base by prefetch timing. Discussed
+# with the kernel security team; no fix, KASLR is not treated as a boundary
+# against local attackers. Distinct from CVE-2023-3640 (cpu_entry_area).
+# https://www.willsroot.io/2022/12/entrybleed.html
+CVE_STATUS[CVE-2022-4543] = "unpatched: no upstream fix, KASLR is not \
+treated as a defence against local attackers"
-- 
2.43.0