* [PATCH 1/2] uio: change to use the mutex lock instead of the spin lock
2018-07-05 16:27 [PATCH 0/2] uio: fix potential crash bug xiubli
@ 2018-07-05 16:27 ` xiubli
2018-07-05 16:33 ` Greg KH
2018-07-05 16:27 ` [PATCH 2/2] uio: fix crash after the device is unregistered xiubli
1 sibling, 1 reply; 7+ messages in thread
From: xiubli @ 2018-07-05 16:27 UTC (permalink / raw)
To: gregkh, linux-kernel; +Cc: pkalever, pkarampu, atumball, sabose, mchristi
From: Xiubo Li <xiubli@redhat.com>
We are hitting a regression with the following commit:
commit a93e7b331568227500186a465fee3c2cb5dffd1f
Author: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Date: Mon May 14 13:32:23 2018 +1200
uio: Prevent device destruction while fds are open
The problem is the addition of spin_lock_irqsave in uio_write. This
leads to hitting uio_write -> copy_from_user -> _copy_from_user ->
might_fault and the logs filling up with sleeping warnings.
I also noticed some uio drivers allocate memory, sleep, grab mutexes
from callouts like open() and release and uio is now doing
spin_lock_irqsave while calling them.
Reported-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
drivers/uio/uio.c | 33 ++++++++++++++-------------------
include/linux/uio_driver.h | 2 +-
2 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index e8f4ac9..33c3bfe 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -433,7 +433,6 @@ static int uio_open(struct inode *inode, struct file *filep)
struct uio_device *idev;
struct uio_listener *listener;
int ret = 0;
- unsigned long flags;
mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode));
@@ -460,10 +459,10 @@ static int uio_open(struct inode *inode, struct file *filep)
listener->event_count = atomic_read(&idev->event);
filep->private_data = listener;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (idev->info && idev->info->open)
ret = idev->info->open(idev->info, inode);
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
if (ret)
goto err_infoopen;
@@ -495,12 +494,11 @@ static int uio_release(struct inode *inode, struct file *filep)
int ret = 0;
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (idev->info && idev->info->release)
ret = idev->info->release(idev->info, inode);
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
module_put(idev->owner);
kfree(listener);
@@ -513,12 +511,12 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
__poll_t ret = 0;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
ret = -EIO;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
+ if (!idev->info || !idev->info->irq)
if (ret)
return ret;
@@ -537,12 +535,11 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
DECLARE_WAITQUEUE(wait, current);
ssize_t retval = 0;
s32 event_count;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
retval = -EIO;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
if (retval)
return retval;
@@ -592,9 +589,8 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
struct uio_device *idev = listener->dev;
ssize_t retval;
s32 irq_on;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq) {
retval = -EIO;
goto out;
@@ -618,7 +614,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
retval = idev->info->irqcontrol(idev->info, irq_on);
out:
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
return retval ? retval : sizeof(s32);
}
@@ -865,7 +861,7 @@ int __uio_register_device(struct module *owner,
idev->owner = owner;
idev->info = info;
- spin_lock_init(&idev->info_lock);
+ mutex_init(&idev->info_lock);
init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0);
@@ -928,7 +924,6 @@ int __uio_register_device(struct module *owner,
void uio_unregister_device(struct uio_info *info)
{
struct uio_device *idev;
- unsigned long flags;
if (!info || !info->uio_dev)
return;
@@ -942,9 +937,9 @@ void uio_unregister_device(struct uio_info *info)
if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev);
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
idev->info = NULL;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
device_unregister(&idev->dev);
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 6c5f207..6f8b68c 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -75,7 +75,7 @@ struct uio_device {
struct fasync_struct *async_queue;
wait_queue_head_t wait;
struct uio_info *info;
- spinlock_t info_lock;
+ struct mutex info_lock;
struct kobject *map_dir;
struct kobject *portio_dir;
};
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 2/2] uio: fix crash after the device is unregistered
2018-07-05 16:27 [PATCH 0/2] uio: fix potential crash bug xiubli
2018-07-05 16:27 ` [PATCH 1/2] uio: change to use the mutex lock instead of the spin lock xiubli
@ 2018-07-05 16:27 ` xiubli
2018-07-05 20:56 ` Jann Horn
1 sibling, 1 reply; 7+ messages in thread
From: xiubli @ 2018-07-05 16:27 UTC (permalink / raw)
To: gregkh, linux-kernel; +Cc: pkalever, pkarampu, atumball, sabose, mchristi
From: Xiubo Li <xiubli@redhat.com>
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
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
drivers/uio/uio.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 86 insertions(+), 15 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 33c3bfe..2b9268a 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);
+ mutex_unlock(&minor_lock);
+
+out:
+ 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);
+ mutex_unlock(&minor_lock);
+
+out:
+ return ret;
}
static DEVICE_ATTR_RO(version);
@@ -415,8 +441,12 @@ 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 +490,11 @@ 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 +626,11 @@ 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 +676,20 @@ 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 +704,11 @@ 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 +733,7 @@ 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 +775,46 @@ 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_lock(&idev->info_lock);
+ return 0;
}
static const struct file_operations uio_fops = {
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread