From c8952a707556e04374d7b2fdb3a079d63ddf6f2f Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Mon, 8 Aug 2016 16:16:23 -0600 Subject: [PATCH] vfio/pci: Fix NULL pointer oops in error interrupt setup handling There are multiple cases in vfio_pci_set_ctx_trigger_single() where we assume we can safely read from our data pointer without actually checking whether the user has passed any data via the count field. VFIO_IRQ_SET_DATA_NONE in particular is entirely broken since we attempt to pull an int32_t file descriptor out before even checking the data type. The other data types assume the data pointer contains one element of their type as well. In part this is good news because we were previously restricted from doing much sanitization of parameters because it was missed in the past and we didn't want to break existing users. Clearly DATA_NONE is completely broken, so it must not have any users and we can fix it up completely. For DATA_BOOL and DATA_EVENTFD, we'll just protect ourselves, returning error when count is zero since we previously would have oopsed. Signed-off-by: Alex Williamson Reported-by: Chris Thompson Cc: stable@vger.kernel.org Reviewed-by: Eric Auger --- drivers/vfio/pci/vfio_pci_intrs.c | 85 ++++++++++++++++++------------- 1 file changed, 49 insertions(+), 36 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 15ecfc9c5f6c..152b43822ef1 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -564,67 +564,80 @@ static int vfio_pci_set_msi_trigger(struct vfio_pci_device *vdev, } static int vfio_pci_set_ctx_trigger_single(struct eventfd_ctx **ctx, - uint32_t flags, void *data) + unsigned int count, uint32_t flags, + void *data) { - int32_t fd = *(int32_t *)data; - - if (!(flags & VFIO_IRQ_SET_DATA_TYPE_MASK)) - return -EINVAL; - /* DATA_NONE/DATA_BOOL enables loopback testing */ if (flags & VFIO_IRQ_SET_DATA_NONE) { - if (*ctx) - eventfd_signal(*ctx, 1); - return 0; + if (*ctx) { + if (count) { + eventfd_signal(*ctx, 1); + } else { + eventfd_ctx_put(*ctx); + *ctx = NULL; + } + return 0; + } } else if (flags & VFIO_IRQ_SET_DATA_BOOL) { - uint8_t trigger = *(uint8_t *)data; + uint8_t trigger; + + if (!count) + return -EINVAL; + + trigger = *(uint8_t *)data; if (trigger && *ctx) eventfd_signal(*ctx, 1); + + return 0; + } else if (flags & VFIO_IRQ_SET_DATA_EVENTFD) { + int32_t fd; + + if (!count) + return -EINVAL; + + fd = *(int32_t *)data; + if (fd == -1) { + if (*ctx) + eventfd_ctx_put(*ctx); + *ctx = NULL; + } else if (fd >= 0) { + struct eventfd_ctx *efdctx; + + efdctx = eventfd_ctx_fdget(fd); + if (IS_ERR(efdctx)) + return PTR_ERR(efdctx); + + if (*ctx) + eventfd_ctx_put(*ctx); + + *ctx = efdctx; + } return 0; } - /* Handle SET_DATA_EVENTFD */ - if (fd == -1) { - if (*ctx) - eventfd_ctx_put(*ctx); - *ctx = NULL; - return 0; - } else if (fd >= 0) { - struct eventfd_ctx *efdctx; - efdctx = eventfd_ctx_fdget(fd); - if (IS_ERR(efdctx)) - return PTR_ERR(efdctx); - if (*ctx) - eventfd_ctx_put(*ctx); - *ctx = efdctx; - return 0; - } else - return -EINVAL; + return -EINVAL; } static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev, unsigned index, unsigned start, unsigned count, uint32_t flags, void *data) { - if (index != VFIO_PCI_ERR_IRQ_INDEX) + if (index != VFIO_PCI_ERR_IRQ_INDEX || start != 0 || count > 1) return -EINVAL; - /* - * We should sanitize start & count, but that wasn't caught - * originally, so this IRQ index must forever ignore them :-( - */ - - return vfio_pci_set_ctx_trigger_single(&vdev->err_trigger, flags, data); + return vfio_pci_set_ctx_trigger_single(&vdev->err_trigger, + count, flags, data); } static int vfio_pci_set_req_trigger(struct vfio_pci_device *vdev, unsigned index, unsigned start, unsigned count, uint32_t flags, void *data) { - if (index != VFIO_PCI_REQ_IRQ_INDEX || start != 0 || count != 1) + if (index != VFIO_PCI_REQ_IRQ_INDEX || start != 0 || count > 1) return -EINVAL; - return vfio_pci_set_ctx_trigger_single(&vdev->req_trigger, flags, data); + return vfio_pci_set_ctx_trigger_single(&vdev->req_trigger, + count, flags, data); } int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,