2021-10-08 06:28:25

by guangming.cao

Subject: [PATCH] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <[email protected]>

Because dma-buf.name can be freed in func: "dma_buf_set_name",
so, we need to acquire lock first before we read/write dma_buf.name
to prevent Use After Free(UAF) issue.

Signed-off-by: Guangming Cao <[email protected]>
---
drivers/dma-buf/dma-buf.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..aebb51b3ff52 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -80,7 +80,9 @@ static void dma_buf_release(struct dentry *dentry)
dma_resv_fini(dmabuf->resv);

module_put(dmabuf->owner);
+ spin_lock(&dmabuf->name_lock);
kfree(dmabuf->name);
+ spin_unlock(&dmabuf->name_lock);
kfree(dmabuf);
}

@@ -1372,6 +1374,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
if (ret)
goto error_unlock;

+
+ spin_lock(&dmabuf->name_lock);
seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
buf_obj->size,
buf_obj->file->f_flags, buf_obj->file->f_mode,
@@ -1379,6 +1383,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
buf_obj->exp_name,
file_inode(buf_obj->file)->i_ino,
buf_obj->name ?: "");
+ spin_unlock(&dmabuf->name_lock);

robj = buf_obj->resv;
fence = dma_resv_excl_fence(robj);
--
2.17.1

2021-10-08 06:40:32

by Christian König

Subject: Re: [PATCH] dma-buf: acquire name lock before read/write dma_buf.name

Am 08.10.21 um 08:29 schrieb [email protected]:
> From: Guangming Cao <[email protected]>
>
> Because dma-buf.name can be freed in func: "dma_buf_set_name",
> so, we need to acquire lock first before we read/write dma_buf.name
> to prevent Use After Free(UAF) issue.
>
> Signed-off-by: Guangming Cao <[email protected]>
> ---
> drivers/dma-buf/dma-buf.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 511fe0d217a0..aebb51b3ff52 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -80,7 +80,9 @@ static void dma_buf_release(struct dentry *dentry)
> dma_resv_fini(dmabuf->resv);
>
> module_put(dmabuf->owner);
> + spin_lock(&dmabuf->name_lock);
> kfree(dmabuf->name);
> + spin_unlock(&dmabuf->name_lock);

That here is certainly a NAK. This is the release function if somebody
is changing the name on a released DMA-buf we have much bigger problems.

> kfree(dmabuf);
> }
>
> @@ -1372,6 +1374,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> if (ret)
> goto error_unlock;
>
> +
> + spin_lock(&dmabuf->name_lock);
> seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
> buf_obj->size,
> buf_obj->file->f_flags, buf_obj->file->f_mode,
> @@ -1379,6 +1383,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> buf_obj->exp_name,
> file_inode(buf_obj->file)->i_ino,
> buf_obj->name ?: "");
> + spin_unlock(&dmabuf->name_lock);

Yeah, that part looks like a good idea to me as well.

Christian.

>
> robj = buf_obj->resv;
> fence = dma_resv_excl_fence(robj);

2021-10-08 07:54:19

by guangming.cao

Subject: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <[email protected]>

Because dma-buf.name can be freed in func: "dma_buf_set_name",
so, we need to acquire lock first before we read/write dma_buf.name
to prevent Use After Free(UAF) issue.

Signed-off-by: Guangming Cao <[email protected]>
---
drivers/dma-buf/dma-buf.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..a7f6fd13a635 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
if (ret)
goto error_unlock;

+
+ spin_lock(&buf_obj->name_lock);
seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
buf_obj->size,
buf_obj->file->f_flags, buf_obj->file->f_mode,
@@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
buf_obj->exp_name,
file_inode(buf_obj->file)->i_ino,
buf_obj->name ?: "");
+ spin_unlock(&buf_obj->name_lock);

robj = buf_obj->resv;
fence = dma_resv_excl_fence(robj);
--
2.17.1

2021-10-08 10:27:52

by Christian König

Subject: Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

Am 08.10.21 um 09:54 schrieb [email protected]:
> From: Guangming Cao <[email protected]>
>
> Because dma-buf.name can be freed in func: "dma_buf_set_name",
> so, we need to acquire lock first before we read/write dma_buf.name
> to prevent Use After Free(UAF) issue.
>
> Signed-off-by: Guangming Cao <[email protected]>

Reviewed-by: Christian König <[email protected]>

Going to push that upstream if nobody else objects.

Thanks,
Christian.

> ---
> drivers/dma-buf/dma-buf.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 511fe0d217a0..a7f6fd13a635 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> if (ret)
> goto error_unlock;
>
> +
> + spin_lock(&buf_obj->name_lock);
> seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
> buf_obj->size,
> buf_obj->file->f_flags, buf_obj->file->f_mode,
> @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> buf_obj->exp_name,
> file_inode(buf_obj->file)->i_ino,
> buf_obj->name ?: "");
> + spin_unlock(&buf_obj->name_lock);
>
> robj = buf_obj->resv;
> fence = dma_resv_excl_fence(robj);

2021-10-12 09:08:35

by guangming.cao

Subject: Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <[email protected]>

> Am 08.10.21 um 09:54 schrieb [email protected]:
> > From: Guangming Cao <[email protected]>
> >
> > Because dma-buf.name can be freed in func: "dma_buf_set_name",
> > so, we need to acquire lock first before we read/write dma_buf.name
> > to prevent Use After Free(UAF) issue.
> >
> > Signed-off-by: Guangming Cao <[email protected]>
>
> Reviewed-by: Christian König <[email protected]>
>
> Going to push that upstream if nobody else objects.
>
> Thanks,
> Christian.

I'm sorry to disturb you, actually I need this patch to solve our issues.
Is there any question about it? seems it hasn't been merged into mainline.

Thanks,
Guangming.
>
> > ---
> > drivers/dma-buf/dma-buf.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 511fe0d217a0..a7f6fd13a635 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> > if (ret)
> > goto error_unlock;
> >
> > +
> > + spin_lock(&buf_obj->name_lock);
> > seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
> > buf_obj->size,
> > buf_obj->file->f_flags, buf_obj->file->f_mode,
> > @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> > buf_obj->exp_name,
> > file_inode(buf_obj->file)->i_ino,
> > buf_obj->name ?: "");
> > + spin_unlock(&buf_obj->name_lock);
> >
> > robj = buf_obj->resv;
> > fence = dma_resv_excl_fence(robj);

2021-10-29 02:18:01

by guangming.cao

Subject: Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <[email protected]>

On Fri, 2021-10-08 at 12:24 +0200, Christian König wrote:
> Am 08.10.21 um 09:54 schrieb [email protected]:
> > From: Guangming Cao <[email protected]>
> >
> > Because dma-buf.name can be freed in func: "dma_buf_set_name",
> > so, we need to acquire lock first before we read/write dma_buf.name
> > to prevent Use After Free(UAF) issue.
> >
> > Signed-off-by: Guangming Cao <[email protected]>
>
> Reviewed-by: Christian König <[email protected]>
>
> Going to push that upstream if nobody else objects.
>
> Thanks,
> Christian.

Just a gentle ping for this patch, please kindly let me know how is it going.

>
> > ---
> > drivers/dma-buf/dma-buf.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 511fe0d217a0..a7f6fd13a635 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file
> > *s, void *unused)
> > if (ret)
> > goto error_unlock;
> >
> > +
> > + spin_lock(&buf_obj->name_lock);
> > seq_printf(s,
> > "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
> > buf_obj->size,
> > buf_obj->file->f_flags, buf_obj->file-
> > >f_mode,
> > @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file
> > *s, void *unused)
> > buf_obj->exp_name,
> > file_inode(buf_obj->file)->i_ino,
> > buf_obj->name ?: "");
> > + spin_unlock(&buf_obj->name_lock);
> >
> > robj = buf_obj->resv;
> > fence = dma_resv_excl_fence(robj);
>
>
> _______________________________________________
> Linux-mediatek mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

2021-10-29 07:37:01

by Christian König

Subject: Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

Am 29.10.21 um 04:15 schrieb [email protected]:
> From: Guangming Cao <[email protected]>
>
> On Fri, 2021-10-08 at 12:24 +0200, Christian König wrote:
>> Am 08.10.21 um 09:54 schrieb [email protected]:
>>> From: Guangming Cao <[email protected]>
>>>
>>> Because dma-buf.name can be freed in func: "dma_buf_set_name",
>>> so, we need to acquire lock first before we read/write dma_buf.name
>>> to prevent Use After Free(UAF) issue.
>>>
>>> Signed-off-by: Guangming Cao <[email protected]>
>> Reviewed-by: Christian König <[email protected]>
>>
>> Going to push that upstream if nobody else objects.
>>
>> Thanks,
>> Christian.
> Just a gentle ping for this patch, please kindly let me know how is it going.

Ah, yes. Thanks for the reminder.

I've just pushed this to drm-misc-fixes.

Christian.

>
>>> ---
>>> drivers/dma-buf/dma-buf.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>>> index 511fe0d217a0..a7f6fd13a635 100644
>>> --- a/drivers/dma-buf/dma-buf.c
>>> +++ b/drivers/dma-buf/dma-buf.c
>>> @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file
>>> *s, void *unused)
>>> if (ret)
>>> goto error_unlock;
>>>
>>> +
>>> + spin_lock(&buf_obj->name_lock);
>>> seq_printf(s,
>>> "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
>>> buf_obj->size,
>>> buf_obj->file->f_flags, buf_obj->file-
>>>> f_mode,
>>> @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file
>>> *s, void *unused)
>>> buf_obj->exp_name,
>>> file_inode(buf_obj->file)->i_ino,
>>> buf_obj->name ?: "");
>>> + spin_unlock(&buf_obj->name_lock);
>>>
>>> robj = buf_obj->resv;
>>> fence = dma_resv_excl_fence(robj);
>>
>> _______________________________________________
>> Linux-mediatek mailing list
>> [email protected]
>> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.infradead.org%2Fmailman%2Flistinfo%2Flinux-mediatek&amp;data=04%7C01%7Cchristian.koenig%40amd.com%7C9e95ae08d63d440fc4d108d99a8200c1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637710705542841586%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=HdiD8%2FX853nQ1vD8n0Qsfv93NaHCCIJF6Pb2rOd%2FLOQ%3D&amp;reserved=0