* [PATCH v1 0/2] usb: f_fs: safe operation in ffs_epfile_io()
@ 2022-05-31 9:36 Linyu Yuan
2022-05-31 9:36 ` [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe " Linyu Yuan
2022-05-31 9:36 ` [PATCH v1 2/2] usb: gadget: ffs: change ep->ep " Linyu Yuan
0 siblings, 2 replies; 6+ messages in thread
From: Linyu Yuan @ 2022-05-31 9:36 UTC (permalink / raw)
To: Felipe Balbi, Greg Kroah-Hartman
Cc: linux-usb, Michael Wu, John Keeping, Linyu Yuan
Fix two possible issue in ffs_epfile_io() when operation at blocking mode.
(note: Two changes queue internally for a long time, when I saw Michael Wu
send a patch[1], I also share to him, there is some discussion
but still not get his ACK. now also saw John Keeping comment
the change, this change is doing a little difference, hope it not break
the rules.)
[1]
https://lore.kernel.org/linux-usb/YpUJkxWBNuZiW7Xk@donbot/T/#m52a26046ed0e3ca4e7b4181c7c808f9e6d1f3ba5
Linyu Yuan (2):
usb: gadget: ffs: change ep->status safe in ffs_epfile_io()
usb: gadget: ffs: change ep->ep safe in ffs_epfile_io()
drivers/usb/gadget/function/f_fs.c | 38 +++++++++++++++++++++++---------------
1 file changed, 23 insertions(+), 15 deletions(-)
--
2.7.4
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe in ffs_epfile_io()
2022-05-31 9:36 [PATCH v1 0/2] usb: f_fs: safe operation in ffs_epfile_io() Linyu Yuan
@ 2022-05-31 9:36 ` Linyu Yuan
2022-05-31 11:44 ` John Keeping
2022-05-31 9:36 ` [PATCH v1 2/2] usb: gadget: ffs: change ep->ep " Linyu Yuan
1 sibling, 1 reply; 6+ messages in thread
From: Linyu Yuan @ 2022-05-31 9:36 UTC (permalink / raw)
To: Felipe Balbi, Greg Kroah-Hartman
Cc: linux-usb, Michael Wu, John Keeping, Linyu Yuan
If a task read/write data in blocking mode, it will wait the completion
in ffs_epfile_io(), if function unbind occurs, ffs_func_unbind() will
kfree ffs ep, once the task wake up, it still dereference the ffs ep to
obtain the request status.
Fix it by moving the request status to io_data which is stack-safe.
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
---
drivers/usb/gadget/function/f_fs.c | 32 +++++++++++++++++---------------
1 file changed, 17 insertions(+), 15 deletions(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 4585ee3..dcba835 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -122,8 +122,6 @@ struct ffs_ep {
struct usb_endpoint_descriptor *descs[3];
u8 num;
-
- int status; /* P: epfile->mutex */
};
struct ffs_epfile {
@@ -227,6 +225,9 @@ struct ffs_io_data {
bool use_sg;
struct ffs_data *ffs;
+
+ int status;
+ struct completion done;
};
struct ffs_desc_helper {
@@ -707,12 +708,12 @@ static const struct file_operations ffs_ep0_operations = {
static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
{
+ struct ffs_io_data *io_data = req->context;
+
ENTER();
- if (req->context) {
- struct ffs_ep *ep = _ep->driver_data;
- ep->status = req->status ? req->status : req->actual;
- complete(req->context);
- }
+
+ io_data->status = req->status ? req->status : req->actual;
+ complete(&io_data->done);
}
static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter)
@@ -1050,7 +1051,6 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
WARN(1, "%s: data_len == -EINVAL\n", __func__);
ret = -EINVAL;
} else if (!io_data->aio) {
- DECLARE_COMPLETION_ONSTACK(done);
bool interrupted = false;
req = ep->req;
@@ -1066,7 +1066,8 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
io_data->buf = data;
- req->context = &done;
+ init_completion(&io_data->done);
+ req->context = io_data;
req->complete = ffs_epfile_io_complete;
ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
@@ -1075,7 +1076,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
spin_unlock_irq(&epfile->ffs->eps_lock);
- if (wait_for_completion_interruptible(&done)) {
+ if (wait_for_completion_interruptible(&io_data->done)) {
/*
* To avoid race condition with ffs_epfile_io_complete,
* dequeue the request first then check
@@ -1083,17 +1084,18 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
* condition with req->complete callback.
*/
usb_ep_dequeue(ep->ep, req);
- wait_for_completion(&done);
- interrupted = ep->status < 0;
+ wait_for_completion(&io_data->done);
+ interrupted = true;
}
if (interrupted)
ret = -EINTR;
- else if (io_data->read && ep->status > 0)
- ret = __ffs_epfile_read_data(epfile, data, ep->status,
+ else if (io_data->read && io_data->status > 0)
+ ret = __ffs_epfile_read_data(epfile, data, io_data->status,
&io_data->data);
else
- ret = ep->status;
+ ret = io_data->status;
+
goto error_mutex;
} else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) {
ret = -ENOMEM;
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v1 2/2] usb: gadget: ffs: change ep->ep safe in ffs_epfile_io()
2022-05-31 9:36 [PATCH v1 0/2] usb: f_fs: safe operation in ffs_epfile_io() Linyu Yuan
2022-05-31 9:36 ` [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe " Linyu Yuan
@ 2022-05-31 9:36 ` Linyu Yuan
2022-05-31 11:47 ` John Keeping
1 sibling, 1 reply; 6+ messages in thread
From: Linyu Yuan @ 2022-05-31 9:36 UTC (permalink / raw)
To: Felipe Balbi, Greg Kroah-Hartman
Cc: linux-usb, Michael Wu, John Keeping, Linyu Yuan
In ffs_epfile_io(), when read/write data in blocking mode, it will wait
the completion in interruptible mode, if task receive a signal, it will
terminate the wait, at same time, if function unbind occurs,
ffs_func_unbind() will kfree all eps, ffs_epfile_io() still try to
dequeue request by dereferencing ep which may become invalid.
Fix it by add ep spinlock and will not dereference ep if it is not valid.
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
---
drivers/usb/gadget/function/f_fs.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index dcba835..b6c9b44 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1077,6 +1077,11 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
spin_unlock_irq(&epfile->ffs->eps_lock);
if (wait_for_completion_interruptible(&io_data->done)) {
+ spin_lock_irq(&epfile->ffs->eps_lock);
+ if (epfile->ep != ep) {
+ ret = -ESHUTDOWN;
+ goto error_lock;
+ }
/*
* To avoid race condition with ffs_epfile_io_complete,
* dequeue the request first then check
@@ -1084,6 +1089,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
* condition with req->complete callback.
*/
usb_ep_dequeue(ep->ep, req);
+ spin_unlock_irq(&epfile->ffs->eps_lock);
wait_for_completion(&io_data->done);
interrupted = true;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe in ffs_epfile_io()
2022-05-31 9:36 ` [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe " Linyu Yuan
@ 2022-05-31 11:44 ` John Keeping
2022-05-31 13:06 ` Linyu Yuan
0 siblings, 1 reply; 6+ messages in thread
From: John Keeping @ 2022-05-31 11:44 UTC (permalink / raw)
To: Linyu Yuan; +Cc: Felipe Balbi, Greg Kroah-Hartman, linux-usb, Michael Wu
On Tue, May 31, 2022 at 05:36:14PM +0800, Linyu Yuan wrote:
> If a task read/write data in blocking mode, it will wait the completion
> in ffs_epfile_io(), if function unbind occurs, ffs_func_unbind() will
> kfree ffs ep, once the task wake up, it still dereference the ffs ep to
> obtain the request status.
>
> Fix it by moving the request status to io_data which is stack-safe.
>
> Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
One minor issue below, but otherwise I like this approach and it will
help solving a similar issue on the AIO path which I spotted while
looking into this (ffs_func_unbind() calls ffs_func_eps_disable()
setting epfile->ep = NULL before draining the completion workqueue where
ffs_user_copy_worker() relies on epfile->ep being non-null).
> ---
> drivers/usb/gadget/function/f_fs.c | 32 +++++++++++++++++---------------
> 1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index 4585ee3..dcba835 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -122,8 +122,6 @@ struct ffs_ep {
> struct usb_endpoint_descriptor *descs[3];
>
> u8 num;
> -
> - int status; /* P: epfile->mutex */
> };
>
> struct ffs_epfile {
> @@ -227,6 +225,9 @@ struct ffs_io_data {
> bool use_sg;
>
> struct ffs_data *ffs;
> +
> + int status;
> + struct completion done;
> };
>
> struct ffs_desc_helper {
> @@ -707,12 +708,12 @@ static const struct file_operations ffs_ep0_operations = {
>
> static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
> {
> + struct ffs_io_data *io_data = req->context;
> +
> ENTER();
> - if (req->context) {
> - struct ffs_ep *ep = _ep->driver_data;
> - ep->status = req->status ? req->status : req->actual;
> - complete(req->context);
> - }
> +
> + io_data->status = req->status ? req->status : req->actual;
> + complete(&io_data->done);
> }
>
> static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter)
> @@ -1050,7 +1051,6 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
> WARN(1, "%s: data_len == -EINVAL\n", __func__);
> ret = -EINVAL;
> } else if (!io_data->aio) {
> - DECLARE_COMPLETION_ONSTACK(done);
> bool interrupted = false;
>
> req = ep->req;
> @@ -1066,7 +1066,8 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>
> io_data->buf = data;
>
> - req->context = &done;
> + init_completion(&io_data->done);
> + req->context = io_data;
> req->complete = ffs_epfile_io_complete;
>
> ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
> @@ -1075,7 +1076,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>
> spin_unlock_irq(&epfile->ffs->eps_lock);
>
> - if (wait_for_completion_interruptible(&done)) {
> + if (wait_for_completion_interruptible(&io_data->done)) {
> /*
> * To avoid race condition with ffs_epfile_io_complete,
> * dequeue the request first then check
> @@ -1083,17 +1084,18 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
> * condition with req->complete callback.
> */
> usb_ep_dequeue(ep->ep, req);
> - wait_for_completion(&done);
> - interrupted = ep->status < 0;
> + wait_for_completion(&io_data->done);
> + interrupted = true;
This is a change in behaviour - shouldn't this be:
interrupted = io_data->status;
?
Otherwise data is lost unnecessarily if the request completes
successfully in the small window between cancellation and being
dequeued.
> }
>
> if (interrupted)
> ret = -EINTR;
> - else if (io_data->read && ep->status > 0)
> - ret = __ffs_epfile_read_data(epfile, data, ep->status,
> + else if (io_data->read && io_data->status > 0)
> + ret = __ffs_epfile_read_data(epfile, data, io_data->status,
> &io_data->data);
> else
> - ret = ep->status;
> + ret = io_data->status;
> +
> goto error_mutex;
> } else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) {
> ret = -ENOMEM;
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 2/2] usb: gadget: ffs: change ep->ep safe in ffs_epfile_io()
2022-05-31 9:36 ` [PATCH v1 2/2] usb: gadget: ffs: change ep->ep " Linyu Yuan
@ 2022-05-31 11:47 ` John Keeping
0 siblings, 0 replies; 6+ messages in thread
From: John Keeping @ 2022-05-31 11:47 UTC (permalink / raw)
To: Linyu Yuan; +Cc: Felipe Balbi, Greg Kroah-Hartman, linux-usb, Michael Wu
On Tue, May 31, 2022 at 05:36:15PM +0800, Linyu Yuan wrote:
> In ffs_epfile_io(), when read/write data in blocking mode, it will wait
> the completion in interruptible mode, if task receive a signal, it will
> terminate the wait, at same time, if function unbind occurs,
> ffs_func_unbind() will kfree all eps, ffs_epfile_io() still try to
> dequeue request by dereferencing ep which may become invalid.
>
> Fix it by add ep spinlock and will not dereference ep if it is not valid.
>
> Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Reviewed-by: John Keeping <john@metanate.com>
> ---
> drivers/usb/gadget/function/f_fs.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index dcba835..b6c9b44 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -1077,6 +1077,11 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
> spin_unlock_irq(&epfile->ffs->eps_lock);
>
> if (wait_for_completion_interruptible(&io_data->done)) {
> + spin_lock_irq(&epfile->ffs->eps_lock);
> + if (epfile->ep != ep) {
> + ret = -ESHUTDOWN;
> + goto error_lock;
> + }
> /*
> * To avoid race condition with ffs_epfile_io_complete,
> * dequeue the request first then check
> @@ -1084,6 +1089,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
> * condition with req->complete callback.
> */
> usb_ep_dequeue(ep->ep, req);
> + spin_unlock_irq(&epfile->ffs->eps_lock);
> wait_for_completion(&io_data->done);
> interrupted = true;
> }
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe in ffs_epfile_io()
2022-05-31 11:44 ` John Keeping
@ 2022-05-31 13:06 ` Linyu Yuan
0 siblings, 0 replies; 6+ messages in thread
From: Linyu Yuan @ 2022-05-31 13:06 UTC (permalink / raw)
To: John Keeping; +Cc: Felipe Balbi, Greg Kroah-Hartman, linux-usb, Michael Wu
On 5/31/2022 7:44 PM, John Keeping wrote:
> On Tue, May 31, 2022 at 05:36:14PM +0800, Linyu Yuan wrote:
>> If a task read/write data in blocking mode, it will wait the completion
>> in ffs_epfile_io(), if function unbind occurs, ffs_func_unbind() will
>> kfree ffs ep, once the task wake up, it still dereference the ffs ep to
>> obtain the request status.
>>
>> Fix it by moving the request status to io_data which is stack-safe.
>>
>> Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
> One minor issue below, but otherwise I like this approach and it will
> help solving a similar issue on the AIO path which I spotted while
> looking into this (ffs_func_unbind() calls ffs_func_eps_disable()
> setting epfile->ep = NULL before draining the completion workqueue where
> ffs_user_copy_worker() relies on epfile->ep being non-null).
>
>> ---
>> drivers/usb/gadget/function/f_fs.c | 32 +++++++++++++++++---------------
>> 1 file changed, 17 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
>> index 4585ee3..dcba835 100644
>> --- a/drivers/usb/gadget/function/f_fs.c
>> +++ b/drivers/usb/gadget/function/f_fs.c
>> @@ -122,8 +122,6 @@ struct ffs_ep {
>> struct usb_endpoint_descriptor *descs[3];
>>
>> u8 num;
>> -
>> - int status; /* P: epfile->mutex */
>> };
>>
>> struct ffs_epfile {
>> @@ -227,6 +225,9 @@ struct ffs_io_data {
>> bool use_sg;
>>
>> struct ffs_data *ffs;
>> +
>> + int status;
>> + struct completion done;
>> };
>>
>> struct ffs_desc_helper {
>> @@ -707,12 +708,12 @@ static const struct file_operations ffs_ep0_operations = {
>>
>> static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
>> {
>> + struct ffs_io_data *io_data = req->context;
>> +
>> ENTER();
>> - if (req->context) {
>> - struct ffs_ep *ep = _ep->driver_data;
>> - ep->status = req->status ? req->status : req->actual;
>> - complete(req->context);
>> - }
>> +
>> + io_data->status = req->status ? req->status : req->actual;
>> + complete(&io_data->done);
>> }
>>
>> static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter)
>> @@ -1050,7 +1051,6 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>> WARN(1, "%s: data_len == -EINVAL\n", __func__);
>> ret = -EINVAL;
>> } else if (!io_data->aio) {
>> - DECLARE_COMPLETION_ONSTACK(done);
>> bool interrupted = false;
>>
>> req = ep->req;
>> @@ -1066,7 +1066,8 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>>
>> io_data->buf = data;
>>
>> - req->context = &done;
>> + init_completion(&io_data->done);
>> + req->context = io_data;
>> req->complete = ffs_epfile_io_complete;
>>
>> ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
>> @@ -1075,7 +1076,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>>
>> spin_unlock_irq(&epfile->ffs->eps_lock);
>>
>> - if (wait_for_completion_interruptible(&done)) {
>> + if (wait_for_completion_interruptible(&io_data->done)) {
>> /*
>> * To avoid race condition with ffs_epfile_io_complete,
>> * dequeue the request first then check
>> @@ -1083,17 +1084,18 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>> * condition with req->complete callback.
>> */
>> usb_ep_dequeue(ep->ep, req);
>> - wait_for_completion(&done);
>> - interrupted = ep->status < 0;
>> + wait_for_completion(&io_data->done);
>> + interrupted = true;
> This is a change in behaviour - shouldn't this be:
>
> interrupted = io_data->status;
>
> ?
>
> Otherwise data is lost unnecessarily if the request completes
> successfully in the small window between cancellation and being
> dequeued.
thanks for explanation, will follow your suggestion in V2.
>> }
>>
>> if (interrupted)
>> ret = -EINTR;
>> - else if (io_data->read && ep->status > 0)
>> - ret = __ffs_epfile_read_data(epfile, data, ep->status,
>> + else if (io_data->read && io_data->status > 0)
>> + ret = __ffs_epfile_read_data(epfile, data, io_data->status,
>> &io_data->data);
>> else
>> - ret = ep->status;
>> + ret = io_data->status;
>> +
>> goto error_mutex;
>> } else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) {
>> ret = -ENOMEM;
>> --
>> 2.7.4
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-05-31 13:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-05-31 9:36 [PATCH v1 0/2] usb: f_fs: safe operation in ffs_epfile_io() Linyu Yuan
2022-05-31 9:36 ` [PATCH v1 1/2] usb: gadget: ffs: change ep->status safe " Linyu Yuan
2022-05-31 11:44 ` John Keeping
2022-05-31 13:06 ` Linyu Yuan
2022-05-31 9:36 ` [PATCH v1 2/2] usb: gadget: ffs: change ep->ep " Linyu Yuan
2022-05-31 11:47 ` John Keeping
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