NULL pointer dereference is observed while exporting the dmabuf but
failed to allocate the 'struct file' which results into the dropping of
the allocated dentry corresponding to this file in the dmabuf fs, which
is ending up in dma_buf_release() and accessing the uninitialzed
dentry->d_fsdata.
Call stack on 5.4 is below:
dma_buf_release+0x2c/0x254 drivers/dma-buf/dma-buf.c:88
__dentry_kill+0x294/0x31c fs/dcache.c:584
dentry_kill fs/dcache.c:673 [inline]
dput+0x250/0x380 fs/dcache.c:859
path_put+0x24/0x40 fs/namei.c:485
alloc_file_pseudo+0x1a4/0x200 fs/file_table.c:235
dma_buf_getfile drivers/dma-buf/dma-buf.c:473 [inline]
dma_buf_export+0x25c/0x3ec drivers/dma-buf/dma-buf.c:585
Fix this by checking for the valid pointer in the dentry->d_fsdata.
Fixes: 4ab59c3c638c ("dma-buf: Move dma_buf_release() from fops to dentry_ops")
Cc: <[email protected]> [5.7+]
Signed-off-by: Charan Teja Reddy <[email protected]>
---
drivers/dma-buf/dma-buf.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 58564d82..844967f 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -59,6 +59,8 @@ static void dma_buf_release(struct dentry *dentry)
struct dma_buf *dmabuf;
dmabuf = dentry->d_fsdata;
+ if (unlikely(!dmabuf))
+ return;
BUG_ON(dmabuf->vmapping_counter);
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation
Am 18.09.20 um 12:32 schrieb Charan Teja Reddy:
> NULL pointer dereference is observed while exporting the dmabuf but
> failed to allocate the 'struct file' which results into the dropping of
> the allocated dentry corresponding to this file in the dmabuf fs, which
> is ending up in dma_buf_release() and accessing the uninitialzed
> dentry->d_fsdata.
>
> Call stack on 5.4 is below:
> dma_buf_release+0x2c/0x254 drivers/dma-buf/dma-buf.c:88
> __dentry_kill+0x294/0x31c fs/dcache.c:584
> dentry_kill fs/dcache.c:673 [inline]
> dput+0x250/0x380 fs/dcache.c:859
> path_put+0x24/0x40 fs/namei.c:485
> alloc_file_pseudo+0x1a4/0x200 fs/file_table.c:235
> dma_buf_getfile drivers/dma-buf/dma-buf.c:473 [inline]
> dma_buf_export+0x25c/0x3ec drivers/dma-buf/dma-buf.c:585
>
> Fix this by checking for the valid pointer in the dentry->d_fsdata.
>
> Fixes: 4ab59c3c638c ("dma-buf: Move dma_buf_release() from fops to dentry_ops")
> Cc: <[email protected]> [5.7+]
> Signed-off-by: Charan Teja Reddy <[email protected]>
Reviewed-by: Christian König <[email protected]>
Going to pick this up for inclusion into drm-misc-next as well.
> ---
> drivers/dma-buf/dma-buf.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 58564d82..844967f 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -59,6 +59,8 @@ static void dma_buf_release(struct dentry *dentry)
> struct dma_buf *dmabuf;
>
> dmabuf = dentry->d_fsdata;
> + if (unlikely(!dmabuf))
> + return;
>
> BUG_ON(dmabuf->vmapping_counter);
>
On Fri, Sep 18, 2020 at 01:16:16PM +0200, Christian K?nig wrote:
> Am 18.09.20 um 12:32 schrieb Charan Teja Reddy:
> > NULL pointer dereference is observed while exporting the dmabuf but
> > failed to allocate the 'struct file' which results into the dropping of
> > the allocated dentry corresponding to this file in the dmabuf fs, which
> > is ending up in dma_buf_release() and accessing the uninitialzed
> > dentry->d_fsdata.
> >
> > Call stack on 5.4 is below:
> > dma_buf_release+0x2c/0x254 drivers/dma-buf/dma-buf.c:88
> > __dentry_kill+0x294/0x31c fs/dcache.c:584
> > dentry_kill fs/dcache.c:673 [inline]
> > dput+0x250/0x380 fs/dcache.c:859
> > path_put+0x24/0x40 fs/namei.c:485
> > alloc_file_pseudo+0x1a4/0x200 fs/file_table.c:235
> > dma_buf_getfile drivers/dma-buf/dma-buf.c:473 [inline]
> > dma_buf_export+0x25c/0x3ec drivers/dma-buf/dma-buf.c:585
> >
> > Fix this by checking for the valid pointer in the dentry->d_fsdata.
> >
> > Fixes: 4ab59c3c638c ("dma-buf: Move dma_buf_release() from fops to dentry_ops")
> > Cc: <[email protected]> [5.7+]
> > Signed-off-by: Charan Teja Reddy <[email protected]>
>
> Reviewed-by: Christian K?nig <[email protected]>
>
> Going to pick this up for inclusion into drm-misc-next as well.
drm-misc-fixes since this is a bugfix that needs to be backported.
-Daniel
>
> > ---
> > drivers/dma-buf/dma-buf.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 58564d82..844967f 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -59,6 +59,8 @@ static void dma_buf_release(struct dentry *dentry)
> > struct dma_buf *dmabuf;
> > dmabuf = dentry->d_fsdata;
> > + if (unlikely(!dmabuf))
> > + return;
> > BUG_ON(dmabuf->vmapping_counter);
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch