diff options
| author | Kirill A. Shutemov <[email protected]> | 2023-10-12 13:04:24 +0300 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2023-10-12 20:27:16 +0200 |
| commit | d35652a5fc9944784f6f50a5c979518ff8dacf61 (patch) | |
| tree | 84eef8447fa8d2feb9a54080567e34ab252d3de2 /scripts/gdb/linux/utils.py | |
| parent | f454b18e07f518bcd0c05af17a2239138bff52de (diff) | |
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 ]
Fixes: 6657fca06e3f ("x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y")
Reported-by: Fei Yang <[email protected]>
Signed-off-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Diffstat (limited to 'scripts/gdb/linux/utils.py')
0 files changed, 0 insertions, 0 deletions