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Message-ID: <3bf1390c-3823-43cd-8b5c-9b0848450628@arm.com>
Date: Thu, 17 Oct 2024 13:09:29 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Ilkka Koskinen <ilkka@...amperecomputing.com>,
Gavin Shan <gshan@...hat.com>, Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>, Joey Gouly <joey.gouly@....com>,
Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu
<yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Akihiko Odaki <akihiko.odaki@...nix.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] KVM: arm64: Fix shift-out-of-bounds bug
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@...r.kernel.org
> Reviewed-by: Gavin Shan <gshan@...hat.com>
> Signed-off-by: Ilkka Koskinen <ilkka@...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@....com>
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