From 94aa033efcac47b09db22cb561e135baf37b7887 Mon Sep 17 00:00:00 2001 From: Jens Freimann Date: Mon, 16 Mar 2015 12:17:13 +0100 Subject: [PATCH] KVM: s390: fix get_all_floating_irqs This fixes a bug introduced with commit c05c4186bbe4 ("KVM: s390: add floating irq controller"). get_all_floating_irqs() does copy_to_user() while holding a spin lock. Let's fix this by filling a temporary buffer first and copy it to userspace after giving up the lock. Cc: # 3.18+: 69a8d4562638 KVM: s390: no need to hold... Reviewed-by: David Hildenbrand Signed-off-by: Jens Freimann Signed-off-by: Christian Borntraeger Acked-by: Cornelia Huck --- Documentation/virtual/kvm/devices/s390_flic.txt | 3 ++ arch/s390/kvm/interrupt.c | 58 ++++++++++++++----------- 2 files changed, 35 insertions(+), 26 deletions(-) diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt index 4ceef53164b0..d1ad9d5cae46 100644 --- a/Documentation/virtual/kvm/devices/s390_flic.txt +++ b/Documentation/virtual/kvm/devices/s390_flic.txt @@ -27,6 +27,9 @@ Groups: Copies all floating interrupts into a buffer provided by userspace. When the buffer is too small it returns -ENOMEM, which is the indication for userspace to try again with a bigger buffer. + -ENOBUFS is returned when the allocation of a kernelspace buffer has + failed. + -EFAULT is returned when copying data to userspace failed. All interrupts remain pending, i.e. are not deleted from the list of currently pending interrupts. attr->addr contains the userspace address of the buffer into which all diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 2361b8ed0a50..5ebd500e6400 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -1477,61 +1478,66 @@ void kvm_s390_clear_float_irqs(struct kvm *kvm) spin_unlock(&fi->lock); } -static inline int copy_irq_to_user(struct kvm_s390_interrupt_info *inti, - u8 *addr) +static void inti_to_irq(struct kvm_s390_interrupt_info *inti, + struct kvm_s390_irq *irq) { - struct kvm_s390_irq __user *uptr = (struct kvm_s390_irq __user *) addr; - struct kvm_s390_irq irq = {0}; - - irq.type = inti->type; + irq->type = inti->type; switch (inti->type) { case KVM_S390_INT_PFAULT_INIT: case KVM_S390_INT_PFAULT_DONE: case KVM_S390_INT_VIRTIO: case KVM_S390_INT_SERVICE: - irq.u.ext = inti->ext; + irq->u.ext = inti->ext; break; case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX: - irq.u.io = inti->io; + irq->u.io = inti->io; break; case KVM_S390_MCHK: - irq.u.mchk = inti->mchk; + irq->u.mchk = inti->mchk; break; - default: - return -EINVAL; } - - if (copy_to_user(uptr, &irq, sizeof(irq))) - return -EFAULT; - - return 0; } -static int get_all_floating_irqs(struct kvm *kvm, __u8 *buf, __u64 len) +static int get_all_floating_irqs(struct kvm *kvm, u8 __user *usrbuf, u64 len) { struct kvm_s390_interrupt_info *inti; struct kvm_s390_float_interrupt *fi; + struct kvm_s390_irq *buf; + int max_irqs; int ret = 0; int n = 0; + if (len > KVM_S390_FLIC_MAX_BUFFER || len == 0) + return -EINVAL; + + /* + * We are already using -ENOMEM to signal + * userspace it may retry with a bigger buffer, + * so we need to use something else for this case + */ + buf = vzalloc(len); + if (!buf) + return -ENOBUFS; + + max_irqs = len / sizeof(struct kvm_s390_irq); + fi = &kvm->arch.float_int; spin_lock(&fi->lock); - list_for_each_entry(inti, &fi->list, list) { - if (len < sizeof(struct kvm_s390_irq)) { + if (n == max_irqs) { /* signal userspace to try again */ ret = -ENOMEM; break; } - ret = copy_irq_to_user(inti, buf); - if (ret) - break; - buf += sizeof(struct kvm_s390_irq); - len -= sizeof(struct kvm_s390_irq); + inti_to_irq(inti, &buf[n]); n++; } - spin_unlock(&fi->lock); + if (!ret && n > 0) { + if (copy_to_user(usrbuf, buf, sizeof(struct kvm_s390_irq) * n)) + ret = -EFAULT; + } + vfree(buf); return ret < 0 ? ret : n; } @@ -1542,7 +1548,7 @@ static int flic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr) switch (attr->group) { case KVM_DEV_FLIC_GET_ALL_IRQS: - r = get_all_floating_irqs(dev->kvm, (u8 *) attr->addr, + r = get_all_floating_irqs(dev->kvm, (u8 __user *) attr->addr, attr->attr); break; default: -- 2.11.0