From: Xiubo Li xiubli@redhat.com
commit 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 upstream.
For the target_core_user use case, after the device is unregistered it maybe still opened in user space, then the kernel will crash, like:
[ 251.163692] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [ 251.163820] IP: [<ffffffffc0736213>] show_name+0x23/0x40 [uio] [ 251.163965] PGD 8000000062694067 PUD 62696067 PMD 0 [ 251.164097] Oops: 0000 [#1] SMP ... [ 251.165605] e1000 mptscsih mptbase drm_panel_orientation_quirks dm_mirror dm_region_hash dm_log dm_mod [ 251.166014] CPU: 0 PID: 13380 Comm: tcmu-runner Kdump: loaded Not tainted 3.10.0-916.el7.test.x86_64 #1 [ 251.166381] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017 [ 251.166747] task: ffff971eb91db0c0 ti: ffff971e9e384000 task.ti: ffff971e9e384000 [ 251.167137] RIP: 0010:[<ffffffffc0736213>] [<ffffffffc0736213>] show_name+0x23/0x40 [uio] [ 251.167563] RSP: 0018:ffff971e9e387dc8 EFLAGS: 00010282 [ 251.167978] RAX: 0000000000000000 RBX: ffff971e9e3f8000 RCX: ffff971eb8368d98 [ 251.168408] RDX: ffff971e9e3f8000 RSI: ffffffffc0738084 RDI: ffff971e9e3f8000 [ 251.168856] RBP: ffff971e9e387dd0 R08: ffff971eb8bc0018 R09: 0000000000000000 [ 251.169296] R10: 0000000000001000 R11: ffffffffa09d444d R12: ffffffffa1076e80 [ 251.169750] R13: ffff971e9e387f18 R14: 0000000000000001 R15: ffff971e9cfb1c80 [ 251.170213] FS: 00007ff37d175880(0000) GS:ffff971ebb600000(0000) knlGS:0000000000000000 [ 251.170693] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 251.171248] CR2: 0000000000000008 CR3: 00000000001f6000 CR4: 00000000003607f0 [ 251.172071] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 251.172640] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 251.173236] Call Trace: [ 251.173789] [<ffffffffa0c9b2d3>] dev_attr_show+0x23/0x60 [ 251.174356] [<ffffffffa0f561b2>] ? mutex_lock+0x12/0x2f [ 251.174892] [<ffffffffa0ac6d9f>] sysfs_kf_seq_show+0xcf/0x1f0 [ 251.175433] [<ffffffffa0ac54e6>] kernfs_seq_show+0x26/0x30 [ 251.175981] [<ffffffffa0a63be0>] seq_read+0x110/0x3f0 [ 251.176609] [<ffffffffa0ac5d45>] kernfs_fop_read+0xf5/0x160 [ 251.177158] [<ffffffffa0a3d3af>] vfs_read+0x9f/0x170 [ 251.177707] [<ffffffffa0a3e27f>] SyS_read+0x7f/0xf0 [ 251.178268] [<ffffffffa0f648af>] system_call_fastpath+0x1c/0x21 [ 251.178823] Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 53 48 89 d3 e8 7e 96 56 e0 48 8b 80 d8 02 00 00 48 89 df 48 c7 c6 84 80 73 c0 <48> 8b 50 08 31 c0 e8 e2 67 44 e0 5b 48 98 5d c3 0f 1f 00 66 2e [ 251.180115] RIP [<ffffffffc0736213>] show_name+0x23/0x40 [uio] [ 251.180820] RSP <ffff971e9e387dc8> [ 251.181473] CR2: 0000000000000008
CC: Hamish Martin hamish.martin@alliedtelesis.co.nz CC: Mike Christie mchristi@redhat.com Reviewed-by: Hamish Martin hamish.martin@alliedtelesis.co.nz Signed-off-by: Xiubo Li xiubli@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Tommi Rantala tommi.t.rantala@nokia.com --- drivers/uio/uio.c | 104 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 88 insertions(+), 16 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 4441235a56cc..262610192755 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -215,7 +215,20 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf) { struct uio_device *idev = dev_get_drvdata(dev); - return sprintf(buf, "%s\n", idev->info->name); + int ret; + + mutex_lock(&idev->info_lock); + if (!idev->info) { + ret = -EINVAL; + dev_err(dev, "the device has been unregistered\n"); + goto out; + } + + ret = sprintf(buf, "%s\n", idev->info->name); + +out: + mutex_unlock(&idev->info_lock); + return ret; } static DEVICE_ATTR_RO(name);
@@ -223,7 +236,20 @@ static ssize_t version_show(struct device *dev, struct device_attribute *attr, char *buf) { struct uio_device *idev = dev_get_drvdata(dev); - return sprintf(buf, "%s\n", idev->info->version); + int ret; + + mutex_lock(&idev->info_lock); + if (!idev->info) { + ret = -EINVAL; + dev_err(dev, "the device has been unregistered\n"); + goto out; + } + + ret = sprintf(buf, "%s\n", idev->info->version); + +out: + mutex_unlock(&idev->info_lock); + return ret; } static DEVICE_ATTR_RO(version);
@@ -417,11 +443,15 @@ EXPORT_SYMBOL_GPL(uio_event_notify); static irqreturn_t uio_interrupt(int irq, void *dev_id) { struct uio_device *idev = (struct uio_device *)dev_id; - irqreturn_t ret = idev->info->handler(irq, idev->info); + irqreturn_t ret; + + mutex_lock(&idev->info_lock);
+ ret = idev->info->handler(irq, idev->info); if (ret == IRQ_HANDLED) uio_event_notify(idev->info);
+ mutex_unlock(&idev->info_lock); return ret; }
@@ -462,6 +492,12 @@ static int uio_open(struct inode *inode, struct file *filep) filep->private_data = listener;
mutex_lock(&idev->info_lock); + if (!idev->info) { + mutex_unlock(&idev->info_lock); + ret = -EINVAL; + goto err_alloc_listener; + } + if (idev->info && idev->info->open) ret = idev->info->open(idev->info, inode); mutex_unlock(&idev->info_lock); @@ -592,6 +628,11 @@ static ssize_t uio_write(struct file *filep, const char __user *buf, s32 irq_on;
mutex_lock(&idev->info_lock); + if (!idev->info) { + retval = -EINVAL; + goto out; + } + if (!idev->info || !idev->info->irq) { retval = -EIO; goto out; @@ -637,10 +678,20 @@ static int uio_vma_fault(struct vm_fault *vmf) struct page *page; unsigned long offset; void *addr; + int ret = 0; + int mi;
- int mi = uio_find_mem_index(vmf->vma); - if (mi < 0) - return VM_FAULT_SIGBUS; + mutex_lock(&idev->info_lock); + if (!idev->info) { + ret = VM_FAULT_SIGBUS; + goto out; + } + + mi = uio_find_mem_index(vmf->vma); + if (mi < 0) { + ret = VM_FAULT_SIGBUS; + goto out; + }
/* * We need to subtract mi because userspace uses offset = N*PAGE_SIZE @@ -655,7 +706,11 @@ static int uio_vma_fault(struct vm_fault *vmf) page = vmalloc_to_page(addr); get_page(page); vmf->page = page; - return 0; + +out: + mutex_unlock(&idev->info_lock); + + return ret; }
static const struct vm_operations_struct uio_logical_vm_ops = { @@ -680,6 +735,7 @@ static int uio_mmap_physical(struct vm_area_struct *vma) struct uio_device *idev = vma->vm_private_data; int mi = uio_find_mem_index(vma); struct uio_mem *mem; + if (mi < 0) return -EINVAL; mem = idev->info->mem + mi; @@ -721,30 +777,46 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
vma->vm_private_data = idev;
+ mutex_lock(&idev->info_lock); + if (!idev->info) { + ret = -EINVAL; + goto out; + } + mi = uio_find_mem_index(vma); - if (mi < 0) - return -EINVAL; + if (mi < 0) { + ret = -EINVAL; + goto out; + }
requested_pages = vma_pages(vma); actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK) + idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT; - if (requested_pages > actual_pages) - return -EINVAL; + if (requested_pages > actual_pages) { + ret = -EINVAL; + goto out; + }
if (idev->info->mmap) { ret = idev->info->mmap(idev->info, vma); - return ret; + goto out; }
switch (idev->info->mem[mi].memtype) { case UIO_MEM_PHYS: - return uio_mmap_physical(vma); + ret = uio_mmap_physical(vma); + break; case UIO_MEM_LOGICAL: case UIO_MEM_VIRTUAL: - return uio_mmap_logical(vma); + ret = uio_mmap_logical(vma); + break; default: - return -EINVAL; + ret = -EINVAL; } + +out: + mutex_unlock(&idev->info_lock); + return 0; }
static const struct file_operations uio_fops = { @@ -943,12 +1015,12 @@ void uio_unregister_device(struct uio_info *info)
uio_free_minor(idev);
+ mutex_lock(&idev->info_lock); uio_dev_del_attributes(idev);
if (info->irq && info->irq != UIO_IRQ_CUSTOM) free_irq(info->irq, idev);
- mutex_lock(&idev->info_lock); idev->info = NULL; mutex_unlock(&idev->info_lock);