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| author | David Matlack <dmatlack@google.com> | 2014-09-19 16:03:25 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-09-24 14:07:55 +0200 |
| commit | 2ea75be3219571d0ec009ce20d9971e54af96e09 (patch) | |
| tree | 04ba1405061760759ee9e911ff660b03be0cf1b5 /virt | |
| parent | 234b239bea395316d7f78018c672f4a88b3cdf0d (diff) | |
| download | linux-stable-2ea75be3219571d0ec009ce20d9971e54af96e09.tar.gz linux-stable-2ea75be3219571d0ec009ce20d9971e54af96e09.tar.bz2 linux-stable-2ea75be3219571d0ec009ce20d9971e54af96e09.zip | |
kvm: don't take vcpu mutex for obviously invalid vcpu ioctls
vcpu ioctls can hang the calling thread if issued while a vcpu is running.
However, invalid ioctls can happen when userspace tries to probe the kind
of file descriptors (e.g. isatty() calls ioctl(TCGETS)); in that case,
we know the ioctl is going to be rejected as invalid anyway and we can
fail before trying to take the vcpu mutex.
This patch does not change functionality, it just makes invalid ioctls
fail faster.
Cc: stable@vger.kernel.org
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1c6e8476b244..ff42b11d2b9c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -52,6 +52,7 @@ #include <asm/processor.h> #include <asm/io.h> +#include <asm/ioctl.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -2032,6 +2033,9 @@ static long kvm_vcpu_ioctl(struct file *filp, if (vcpu->kvm->mm != current->mm) return -EIO; + if (unlikely(_IOC_TYPE(ioctl) != KVMIO)) + return -EINVAL; + #if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) /* * Special cases: vcpu ioctls that are asynchronous to vcpu execution, |