[PATCH V2 2/2] uio: fix crash after the device is unregistered
From: xiubli
Date: Thu Jul 05 2018 - 20:07:07 EST
From: Xiubo Li <xiubli@xxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
CC: Mike Christie <mchristi@xxxxxxxxxx>
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
drivers/uio/uio.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 93 insertions(+), 16 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 33c3bfe..5fe3ca5 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(&minor_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(&minor_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(&minor_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(&minor_lock);
+ return ret;
}
static DEVICE_ATTR_RO(version);
@@ -399,7 +425,12 @@ static void uio_free_minor(struct uio_device *idev)
*/
void uio_event_notify(struct uio_info *info)
{
- struct uio_device *idev = info->uio_dev;
+ struct uio_device *idev;
+
+ if (!info)
+ return;
+
+ idev = info->uio_dev;
atomic_inc(&idev->event);
wake_up_interruptible(&idev->wait);
@@ -415,8 +446,12 @@ void uio_event_notify(struct uio_info *info)
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;
+
+ if (!idev->info)
+ return -EINVAL;
+ ret = idev->info->handler(irq, idev->info);
if (ret == IRQ_HANDLED)
uio_event_notify(idev->info);
@@ -460,6 +495,12 @@ 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);
@@ -591,6 +632,11 @@ 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;
@@ -636,10 +682,20 @@ static vm_fault_t 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
@@ -654,7 +710,11 @@ static vm_fault_t 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 = {
@@ -679,6 +739,7 @@ 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;
@@ -720,30 +781,46 @@ 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 = {
--
1.8.3.1