Commit b21629da authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Radim Krčmář

kvm: x86: avoid warning on repeated KVM_SET_TSS_ADDR

Found by syzkaller:

    WARNING: CPU: 3 PID: 15175 at arch/x86/kvm/x86.c:7705 __x86_set_memory_region+0x1dc/0x1f0 [kvm]()
    CPU: 3 PID: 15175 Comm: a.out Tainted: G        W       4.4.6-300.fc23.x86_64 #1
    Hardware name: LENOVO 2325F51/2325F51, BIOS G2ET32WW (1.12 ) 05/30/2012
     0000000000000286 00000000950899a7 ffff88011ab3fbf0 ffffffff813b542e
     0000000000000000 ffffffffa0966496 ffff88011ab3fc28 ffffffff810a40f2
     00000000000001fd 0000000000003000 ffff88014fc50000 0000000000000000
    Call Trace:
     [<ffffffff813b542e>] dump_stack+0x63/0x85
     [<ffffffff810a40f2>] warn_slowpath_common+0x82/0xc0
     [<ffffffff810a423a>] warn_slowpath_null+0x1a/0x20
     [<ffffffffa09251cc>] __x86_set_memory_region+0x1dc/0x1f0 [kvm]
     [<ffffffffa092521b>] x86_set_memory_region+0x3b/0x60 [kvm]
     [<ffffffffa09bb61c>] vmx_set_tss_addr+0x3c/0x150 [kvm_intel]
     [<ffffffffa092f4d4>] kvm_arch_vm_ioctl+0x654/0xbc0 [kvm]
     [<ffffffffa091d31a>] kvm_vm_ioctl+0x9a/0x6f0 [kvm]
     [<ffffffff81241248>] do_vfs_ioctl+0x298/0x480
     [<ffffffff812414a9>] SyS_ioctl+0x79/0x90
     [<ffffffff817a04ee>] entry_SYSCALL_64_fastpath+0x12/0x71


    #include <unistd.h>
    #include <sys/ioctl.h>
    #include <fcntl.h>
    #include <string.h>
    #include <linux/kvm.h>

    long r[8];

    int main()
        memset(r, -1, sizeof(r));
	r[2] = open("/dev/kvm", O_RDONLY|O_TRUNC);
        r[3] = ioctl(r[2], KVM_CREATE_VM, 0x0ul);
        r[5] = ioctl(r[3], KVM_SET_TSS_ADDR, 0x20000000ul);
        r[7] = ioctl(r[3], KVM_SET_TSS_ADDR, 0x20000000ul);
        return 0;
Reported-by: default avatarDmitry Vyukov <>
Signed-off-by: default avatarPaolo Bonzini <>
Signed-off-by: default avatarRadim Krčmář <>
parent 0c2df2a1
......@@ -7816,7 +7816,7 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
slot = id_to_memslot(slots, id);
if (size) {
if (WARN_ON(slot->npages))
if (slot->npages)
return -EEXIST;
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