From: Sangsup lee <[email protected]>
This patch adds mutex_lock for fixing an Use-after-free bug.
fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
The buf which is allocated by list_for_each_safe can be used after another thread frees it.
Signed-off-by: Sangsup lee <[email protected]>
---
V1 -> V2: moving the locking to ioctl.
drivers/misc/fastrpc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 93ebd174d848..aa1cf0e9f4ed 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
err = fastrpc_req_mmap(fl, argp);
break;
case FASTRPC_IOCTL_MUNMAP:
+ mutex_lock(&fl->mutex);
err = fastrpc_req_munmap(fl, argp);
+ mutex_unlock(&fl->mutex);
break;
case FASTRPC_IOCTL_MEM_MAP:
err = fastrpc_req_mem_map(fl, argp);
--
2.25.1
Is there any comment for this issue?
(reference: https://www.spinics.net/lists/kernel/msg4731408.html)
2023년 3월 23일 (목) 오전 10:37, Sangsup Lee <[email protected]>님이 작성:
>
> From: Sangsup lee <[email protected]>
>
> This patch adds mutex_lock for fixing an Use-after-free bug.
> fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
> The buf which is allocated by list_for_each_safe can be used after another thread frees it.
>
> Signed-off-by: Sangsup lee <[email protected]>
> ---
> V1 -> V2: moving the locking to ioctl.
>
> drivers/misc/fastrpc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 93ebd174d848..aa1cf0e9f4ed 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
> err = fastrpc_req_mmap(fl, argp);
> break;
> case FASTRPC_IOCTL_MUNMAP:
> + mutex_lock(&fl->mutex);
> err = fastrpc_req_munmap(fl, argp);
> + mutex_unlock(&fl->mutex);
> break;
> case FASTRPC_IOCTL_MEM_MAP:
> err = fastrpc_req_mem_map(fl, argp);
> --
> 2.25.1
>
On Thu, Apr 27, 2023 at 06:29:16PM +0900, sangsup lee wrote:
> Is there any comment for this issue?
What issue?
> (reference: https://www.spinics.net/lists/kernel/msg4731408.html)
Please use lore.kernel.org links, we have no control over any other
random email archive .
And the above link just points to this proposed patch.
>
>
> 2023년 3월 23일 (목) 오전 10:37, Sangsup Lee <[email protected]>님이 작성:
> >
> > From: Sangsup lee <[email protected]>
> >
> > This patch adds mutex_lock for fixing an Use-after-free bug.
> > fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
> > The buf which is allocated by list_for_each_safe can be used after another thread frees it.
How was this tested?
> >
> > Signed-off-by: Sangsup lee <[email protected]>
> > ---
> > V1 -> V2: moving the locking to ioctl.
> >
> > drivers/misc/fastrpc.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > index 93ebd174d848..aa1cf0e9f4ed 100644
> > --- a/drivers/misc/fastrpc.c
> > +++ b/drivers/misc/fastrpc.c
> > @@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
> > err = fastrpc_req_mmap(fl, argp);
> > break;
> > case FASTRPC_IOCTL_MUNMAP:
> > + mutex_lock(&fl->mutex);
> > err = fastrpc_req_munmap(fl, argp);
> > + mutex_unlock(&fl->mutex);
Are you sure you can call this function with the lock? If so, why isn't
the mmap ioctl also locked?
thanks,
greg k-h
I reported fastrpc bug in
Feb,2023.(https://lore.kernel.org/lkml/[email protected])
And Srinivas recommended this patch code for patch v2.
That's why I sent this patch v2 however, I haven't received any reply
after that.
I just want to know the next step for patching this code.
Should I just keep waiting ? Or Please let me know if I need to
provide you with more information.
(Ps. I'm sorry, i re-send this reply because of missing text-mode )
Best regards.
2023년 4월 27일 (목) 오후 6:52, Greg Kroah-Hartman <[email protected]>님이 작성:
>
> On Thu, Apr 27, 2023 at 06:29:16PM +0900, sangsup lee wrote:
> > Is there any comment for this issue?
>
> What issue?
>
> > (reference: https://www.spinics.net/lists/kernel/msg4731408.html)
>
> Please use lore.kernel.org links, we have no control over any other
> random email archive .
>
> And the above link just points to this proposed patch.
>
> >
> >
> > 2023년 3월 23일 (목) 오전 10:37, Sangsup Lee <[email protected]>님이 작성:
> > >
> > > From: Sangsup lee <[email protected]>
> > >
> > > This patch adds mutex_lock for fixing an Use-after-free bug.
> > > fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
> > > The buf which is allocated by list_for_each_safe can be used after another thread frees it.
>
> How was this tested?
>
> > >
> > > Signed-off-by: Sangsup lee <[email protected]>
> > > ---
> > > V1 -> V2: moving the locking to ioctl.
> > >
> > > drivers/misc/fastrpc.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > > index 93ebd174d848..aa1cf0e9f4ed 100644
> > > --- a/drivers/misc/fastrpc.c
> > > +++ b/drivers/misc/fastrpc.c
> > > @@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
> > > err = fastrpc_req_mmap(fl, argp);
> > > break;
> > > case FASTRPC_IOCTL_MUNMAP:
> > > + mutex_lock(&fl->mutex);
> > > err = fastrpc_req_munmap(fl, argp);
> > > + mutex_unlock(&fl->mutex);
>
> Are you sure you can call this function with the lock? If so, why isn't
> the mmap ioctl also locked?
>
> thanks,
>
> greg k-h
A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
A: No.
Q: Should I include quotations after my reply?
http://daringfireball.net/2007/07/on_top
On Thu, Apr 27, 2023 at 08:51:48PM +0900, sangsup lee wrote:
> I reported fastrpc bug in
> Feb,2023.(https://lore.kernel.org/lkml/[email protected])
That was a patch, not a bug report. How was this tested?
> And Srinivas recommended this patch code for patch v2.
> That's why I sent this patch v2 however, I haven't received any reply
> after that.
>
> I just want to know the next step for patching this code.
> Should I just keep waiting ? Or Please let me know if I need to
> provide you with more information.
Please read my comments on my last email on the patch for what you need
to address.
thanks,
greg k-h
I apologize for recognizing the email in the TOP POST format. I missed
the comment in the previous email.
2023년 4월 27일 (목) 오후 6:52, Greg Kroah-Hartman <[email protected]>님이 작성:
>
> On Thu, Apr 27, 2023 at 06:29:16PM +0900, sangsup lee wrote:
> > Is there any comment for this issue?
>
> What issue?
>
> > (reference: https://www.spinics.net/lists/kernel/msg4731408.html)
>
> Please use lore.kernel.org links, we have no control over any other
> random email archive .
>
> And the above link just points to this proposed patch.
>
> >
> >
> > 2023년 3월 23일 (목) 오전 10:37, Sangsup Lee <[email protected]>님이 작성:
> > >
> > > From: Sangsup lee <[email protected]>
> > >
> > > This patch adds mutex_lock for fixing an Use-after-free bug.
> > > fastrpc_req_munmap_impl can be called concurrently in multi-threded environments.
> > > The buf which is allocated by list_for_each_safe can be used after another thread frees it.
>
> How was this tested?
>
I was unable to configure the environment in which this code is running.
Therefore, I could not go through dynamic testing for the related issue.
However, I found vulnerabilities in similar types of functions
in other drivers in the mobile environment, so I think this code is
also problematic.
> > >
> > > Signed-off-by: Sangsup lee <[email protected]>
> > > ---
> > > V1 -> V2: moving the locking to ioctl.
> > >
> > > drivers/misc/fastrpc.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > > index 93ebd174d848..aa1cf0e9f4ed 100644
> > > --- a/drivers/misc/fastrpc.c
> > > +++ b/drivers/misc/fastrpc.c
> > > @@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
> > > err = fastrpc_req_mmap(fl, argp);
> > > break;
> > > case FASTRPC_IOCTL_MUNMAP:
> > > + mutex_lock(&fl->mutex);
> > > err = fastrpc_req_munmap(fl, argp);
> > > + mutex_unlock(&fl->mutex);
>
> Are you sure you can call this function with the lock? If so, why isn't
> the mmap ioctl also locked?
I am convinced that FASTRPC_IOCTL_MUNMAP can lead to a race condition bug.
However, as I mentioned in patch v1, I am not an expert in fastrpc.
I worried about the side effects of the code I suggested.
So, I asked you to recommend which code to use, and this is the code
that was recommended to me.
And I didn't check the mmap function because I couldn't find a bug in mmap.
>
> thanks,
>
> greg k-h