Fix the following UBSAN report: ================================================================= UBSAN: Undefined behaviour in include/common.h:322:19 left shift of 1 by 31 places cannot be represented in type 'int' =================================================================
Steps to reproduce the above: * echo CONFIG_UBSAN=y >> configs/qemu-ppce500_defconfig * make ARCH=powerpc CROSS_COMPILE=/usr/bin/powerpc-linux-gnu- \ qemu-ppce500_defconfig all * qemu-system-ppc --version QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.31) * qemu-system-ppc -machine ppce500 -nographic -no-reboot -kernel u-boot
It looks like cpumask_next() intentionally uses shift overflow in its for loop condition to break the loop. Relying on UB is not safe. Convert the numeric literal 1 to 1UL and limit its maximum shift index to 31.
Fixes: fbb9ecf7493f ("powerpc/mp: add support for discontiguous cores") Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com ---
Changes in v2: - None. Newly pushed. --- include/common.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/common.h b/include/common.h index 940161f1758b..5b92666d0e79 100644 --- a/include/common.h +++ b/include/common.h @@ -319,7 +319,7 @@ void trap_init (ulong); /* $(CPU)/cpu.c */ static inline int cpumask_next(int cpu, unsigned int mask) { - for (cpu++; !((1 << cpu) & mask); cpu++) + for (cpu++; (cpu < 31) && !((1UL << cpu) & mask); cpu++) ;
return cpu;