From: Heiko Carstens hca@linux.ibm.com
[ Upstream commit e42ac7789df64120d7d3d57433dfc9f37ec0cb99 ]
Commit dfe843dce775 ("s390/checksum: support GENERIC_CSUM, enable it for KASAN") switched s390 to use the generic checksum functions, so that KASAN instrumentation also works checksum functions by avoiding architecture specific inline assemblies.
There is however the problem that the generic csum_partial() function returns a 32 bit value with a 16 bit folded checksum, while the original s390 variant does not fold to 16 bit. This in turn causes that the ipib_checksum in lowcore contains different values depending on kernel config options.
The ipib_checksum is used by system dumpers to verify if pointers in lowcore point to valid data. Verification is done by comparing checksum values. The system dumpers still use 32 bit checksum values which are not folded, and therefore the checksum verification fails (incorrectly).
Symptom is that reboot after dump does not work anymore when a KASAN instrumented kernel is dumped.
Fix this by not using the generic checksum implementation. Instead add an explicit kasan_check_read() so that KASAN knows about the read access from within the inline assembly.
Reported-by: Alexander Egorenkov egorenar@linux.ibm.com Fixes: dfe843dce775 ("s390/checksum: support GENERIC_CSUM, enable it for KASAN") Tested-by: Alexander Egorenkov egorenar@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/Kconfig | 4 ---- arch/s390/include/asm/checksum.h | 9 ++------- 2 files changed, 2 insertions(+), 11 deletions(-)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 7fd08755a1f9e..854a6581d2f90 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -26,10 +26,6 @@ config GENERIC_BUG config GENERIC_BUG_RELATIVE_POINTERS def_bool y
-config GENERIC_CSUM - bool - default y if KASAN - config GENERIC_LOCKBREAK def_bool y if PREEMPTION
diff --git a/arch/s390/include/asm/checksum.h b/arch/s390/include/asm/checksum.h index d977a3a2f6190..1b6b992cf18ed 100644 --- a/arch/s390/include/asm/checksum.h +++ b/arch/s390/include/asm/checksum.h @@ -12,12 +12,7 @@ #ifndef _S390_CHECKSUM_H #define _S390_CHECKSUM_H
-#ifdef CONFIG_GENERIC_CSUM - -#include <asm-generic/checksum.h> - -#else /* CONFIG_GENERIC_CSUM */ - +#include <linux/kasan-checks.h> #include <linux/uaccess.h> #include <linux/in6.h>
@@ -40,6 +35,7 @@ static inline __wsum csum_partial(const void *buff, int len, __wsum sum) .odd = (unsigned long) len, };
+ kasan_check_read(buff, len); asm volatile( "0: cksm %[sum],%[rp]\n" " jo 0b\n" @@ -135,5 +131,4 @@ static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr, return csum_fold((__force __wsum)(sum >> 32)); }
-#endif /* CONFIG_GENERIC_CSUM */ #endif /* _S390_CHECKSUM_H */