[PATCH] KVM: s390: Add missing vm MEM_OP size check

Janis Schoetterl-Glausch
2022-02-21T16:32:51Z

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@linux.ibm.com>
---
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;
--
2.32.0