[PATCH v2] KVM: arm64: Fix shift-out-of-bounds bug

[Anshuman Khandual]

On 10/17/24 08:27, Ilkka Koskinen wrote:
> Fix a shift-out-of-bounds bug reported by UBSAN when running
> VM with MTE enabled host kernel.
> 
> UBSAN: shift-out-of-bounds in arch/arm64/kvm/sys_regs.c:1988:14
> shift exponent 33 is too large for 32-bit type 'int'
> CPU: 26 UID: 0 PID: 7629 Comm: qemu-kvm Not tainted 6.12.0-rc2 #34
> Hardware name: IEI NF5280R7/Mitchell MB, BIOS 00.00. 2024-10-12 09:28:54 10/14/2024
> Call trace:
>  dump_backtrace+0xa0/0x128
>  show_stack+0x20/0x38
>  dump_stack_lvl+0x74/0x90
>  dump_stack+0x18/0x28
>  __ubsan_handle_shift_out_of_bounds+0xf8/0x1e0
>  reset_clidr+0x10c/0x1c8
>  kvm_reset_sys_regs+0x50/0x1c8
>  kvm_reset_vcpu+0xec/0x2b0
>  __kvm_vcpu_set_target+0x84/0x158
>  kvm_vcpu_set_target+0x138/0x168
>  kvm_arch_vcpu_ioctl_vcpu_init+0x40/0x2b0
>  kvm_arch_vcpu_ioctl+0x28c/0x4b8
>  kvm_vcpu_ioctl+0x4bc/0x7a8
>  __arm64_sys_ioctl+0xb4/0x100
>  invoke_syscall+0x70/0x100
>  el0_svc_common.constprop.0+0x48/0xf0
>  do_el0_svc+0x24/0x38
>  el0_svc+0x3c/0x158
>  el0t_64_sync_handler+0x120/0x130
>  el0t_64_sync+0x194/0x198
> 
> Fixes: 7af0c2534f4c ("KVM: arm64: Normalize cache configuration")
> Cc: stable at vger.kernel.org
> Reviewed-by: Gavin Shan <gshan at redhat.com>
> Signed-off-by: Ilkka Koskinen <ilkka at os.amperecomputing.com>
> ---
>  arch/arm64/kvm/sys_regs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 375052d8cd22..ff8c4e1b847e 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1994,7 +1994,7 @@ static u64 reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
>  	 * one cache line.
>  	 */
>  	if (kvm_has_mte(vcpu->kvm))
> -		clidr |= 2 << CLIDR_TTYPE_SHIFT(loc);
> +		clidr |= 2ULL << CLIDR_TTYPE_SHIFT(loc);
>  
>  	__vcpu_sys_reg(vcpu, r->reg) = clidr;
>  

clidr being u64, 2ULL is preferred over 2UL.

Reviewed-by: Anshuman Khandual <anshuman.khandual at arm.com>