vulnerability
Ubuntu: (Multiple Advisories) (CVE-2023-52504): Linux kernel vulnerabilities
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 6 | (AV:L/AC:L/Au:S/C:C/I:N/A:C) | 03/02/2024 | 07/15/2024 | 01/28/2025 |
Description
In the Linux kernel, the following vulnerability has been resolved:
x86/alternatives: Disable KASAN in apply_alternatives()
Fei has reported that KASAN triggers during apply_alternatives() on
a 5-level paging machine:
BUG: KASAN: out-of-bounds in rcu_is_watching()
Read of size 4 at addr ff110003ee6419a0 by task swapper/0/0
...
__asan_load4()
rcu_is_watching()
trace_hardirqs_on()
text_poke_early()
apply_alternatives()
...
On machines with 5-level paging, cpu_feature_enabled(X86_FEATURE_LA57)
gets patched. It includes KASAN code, where KASAN_SHADOW_START depends on
__VIRTUAL_MASK_SHIFT, which is defined with cpu_feature_enabled().
KASAN gets confused when apply_alternatives() patches the
KASAN_SHADOW_START users. A test patch that makes KASAN_SHADOW_START
static, by replacing __VIRTUAL_MASK_SHIFT with 56, works around the issue.
Fix it for real by disabling KASAN while the kernel is patching alternatives.
[ mingo: updated the changelog ]
Solution(s)
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