linux-kernel - Re: [PATCH] KVM: s390: Add missing vm MEM

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Date:   Tue, 22 Feb 2022 09:04:53 +0100
From:   Christian Borntraeger <borntraeger@...ux.ibm.com>
To:     Janis Schoetterl-Glausch <scgl@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Sven Schnelle <svens@...ux.ibm.com>, kvm@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: s390: Add missing vm MEM_OP size check



Am 21.02.22 um 17:32 schrieb Janis Schoetterl-Glausch:
> Check that size is not zero, preventing the following warning:
> 
> WARNING: CPU: 0 PID: 9692 at mm/vmalloc.c:3059 __vmalloc_node_range+0x528/0x648
> Modules linked in:
> CPU: 0 PID: 9692 Comm: memop Not tainted 5.17.0-rc3-e4+ #80
> Hardware name: IBM 8561 T01 701 (LPAR)
> Krnl PSW : 0704c00180000000 0000000082dc584c (__vmalloc_node_range+0x52c/0x648)
>             R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
> Krnl GPRS: 0000000000000083 ffffffffffffffff 0000000000000000 0000000000000001
>             0000038000000000 000003ff80000000 0000000000000cc0 000000008ebb8000
>             0000000087a8a700 000000004040aeb1 000003ffd9f7dec8 000000008ebb8000
>             000000009d9b8000 000000000102a1b4 00000380035afb68 00000380035afaa8
> Krnl Code: 0000000082dc583e: d028a7f4ff80        trtr    2036(41,%r10),3968(%r15)
>             0000000082dc5844: af000000            mc      0,0
>            #0000000082dc5848: af000000            mc      0,0
>            >0000000082dc584c: a7d90000            lghi    %r13,0
>             0000000082dc5850: b904002d            lgr     %r2,%r13
>             0000000082dc5854: eb6ff1080004        lmg     %r6,%r15,264(%r15)
>             0000000082dc585a: 07fe                bcr     15,%r14
>             0000000082dc585c: 47000700            bc      0,1792
> Call Trace:
>   [<0000000082dc584c>] __vmalloc_node_range+0x52c/0x648
>   [<0000000082dc5b62>] vmalloc+0x5a/0x68
>   [<000003ff8067f4ca>] kvm_arch_vm_ioctl+0x2da/0x2a30 [kvm]
>   [<000003ff806705bc>] kvm_vm_ioctl+0x4ec/0x978 [kvm]
>   [<0000000082e562fe>] __s390x_sys_ioctl+0xbe/0x100
>   [<000000008360a9bc>] __do_syscall+0x1d4/0x200
>   [<0000000083618bd2>] system_call+0x82/0xb0
> Last Breaking-Event-Address:
>   [<0000000082dc5348>] __vmalloc_node_range+0x28/0x648
> 
> Other than the warning, there is no ill effect from the missing check,
> the condition is detected by subsequent code and causes a return
> with ENOMEM.
> 
> Fixes: ef11c9463ae0 (KVM: s390: Add vm IOCTL for key checked guest absolute memory access)
> Signed-off-by: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>

applied to kvms390/next, Thanks.
> ---
>   arch/s390/kvm/kvm-s390.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index c2c26c2aad64..e056ad86ccd2 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2374,7 +2374,7 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>   
>   	supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
>   			  | KVM_S390_MEMOP_F_CHECK_ONLY;
> -	if (mop->flags & ~supported_flags)
> +	if (mop->flags & ~supported_flags || !mop->size)
>   		return -EINVAL;
>   	if (mop->size > MEM_OP_MAX_SIZE)
>   		return -E2BIG;