[PATCH 1/2] powerpc/kdump: fix KASAN sanitization flag for core_$(BITS).o

[Sourabh Jain]

On 23/03/26 11:41, Mahesh J Salgaonkar wrote:
> On 2026-03-21 11:01:17 Sat, Sourabh Jain wrote:
>> KASAN instrumentation is intended to be disabled for the kexec core
>> code, but the existing Makefile entry misses the object suffix. As a
>> result, the flag is not applied correctly to core_$(BITS).o.
>>
>> So when KASAN is enabled, kexec_copy_flush and copy_segments in
>> kexec/core_64.c are instrumented, which can result in accesses to
>> shadow memory via normal address translation paths. Since these run
>> with the MMU disabled, such accesses may trigger page faults
>> (bad_page_fault) that cannot be handled in the kdump path, ultimately
>> causing a hang and preventing the kdump kernel from booting. The same
>> is true for kexec as well, since the same functions are used there.
>>
>> Update the entry to include the “.o” suffix so that KASAN
>> instrumentation is properly disabled for this object file.
>>
>> Fixes: 2ab2d5794f14 ("powerpc/kasan: Disable address sanitization in kexec paths")
>> Reported-by: Venkat Rao Bagalkote <venkat88 at linux.ibm.com>
>> Closes: https://lore.kernel.org/all/1dee8891-8bcc-46b4-93f3-fc3a774abd5b@linux.ibm.com/
>> Cc: Aboorva Devarajan <aboorvad at linux.ibm.com>
>> Cc: Aditya Gupta <adityag at linux.ibm.com>
>> Cc: Daniel Axtens <dja at axtens.net>
>> Cc: Hari Bathini <hbathini at linux.ibm.com>
>> Cc: Madhavan Srinivasan <maddy at linux.ibm.com>
>> Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
>> Cc: Michael Ellerman <mpe at ellerman.id.au>
>> Cc: Ritesh Harjani (IBM) <ritesh.list at gmail.com>
>> Cc: Shivang Upadhyay <shivangu at linux.ibm.com>
>> Signed-off-by: Sourabh Jain <sourabhjain at linux.ibm.com>
>> ---
>>   arch/powerpc/kexec/Makefile | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
>> index 470eb0453e17..ec7a0eed75dc 100644
>> --- a/arch/powerpc/kexec/Makefile
>> +++ b/arch/powerpc/kexec/Makefile
>> @@ -16,4 +16,4 @@ GCOV_PROFILE_core_$(BITS).o := n
>>   KCOV_INSTRUMENT_core_$(BITS).o := n
>>   UBSAN_SANITIZE_core_$(BITS).o := n
>>   KASAN_SANITIZE_core.o := n
>> -KASAN_SANITIZE_core_$(BITS) := n
>> +KASAN_SANITIZE_core_$(BITS).o := n
> Nice catch. Thakns for fixing.
>
> Acked-by: Mahesh Salgaonkar <mahesh at linux.ibm.com>
Thanks for the Ack Mahesh.

- Sourabh Jain