Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Christoph Hellwig
On Tue, Sep 15, 2020 at 04:46:17PM -0400, Thomas Tai wrote: > I tried out the suggested changes, and it successfully warned the null > pointer without panic. I notice that there are some places outside the > dma-direct, which calls dma_capable(). > > https://elixir.bootlin.com/linux/v5.9-rc5/sour

[PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Thomas Tai
When booting the kernel v5.9-rc4 on a VM, the kernel would panic when printing a warning message in swiotlb_map(). It is because dev->dma_mask can potentially be a null pointer. Using the dma_get_mask() macro can avoid the NULL pointer dereference. Fixes: d323bb44e4d2 ("drm/virtio: Call the right

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Christoph Hellwig
On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: > When booting the kernel v5.9-rc4 on a VM, the kernel would panic when > printing a warning message in swiotlb_map(). It is because dev->dma_mask > can potentially be a null pointer. Using the dma_get_mask() macro can > avoid the NULL poi

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Thomas Tai
On 2020-09-15 10:07 a.m., Christoph Hellwig wrote: On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: When booting the kernel v5.9-rc4 on a VM, the kernel would panic when printing a warning message in swiotlb_map(). It is because dev->dma_mask can potentially be a null pointer. Usin

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Christoph Hellwig
On Tue, Sep 15, 2020 at 10:11:51AM -0400, Thomas Tai wrote: > > > On 2020-09-15 10:07 a.m., Christoph Hellwig wrote: >> On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: >>> When booting the kernel v5.9-rc4 on a VM, the kernel would panic when >>> printing a warning message in swiotlb_map

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Thomas Tai
On 2020-09-15 11:09 a.m., Christoph Hellwig wrote: On Tue, Sep 15, 2020 at 10:40:39AM -0400, Thomas Tai wrote: +++ b/include/linux/dma-direct.h @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, { dma_addr_t end = addr + size - 1;

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Thomas Tai
On 2020-09-15 11:09 a.m., Christoph Hellwig wrote: On Tue, Sep 15, 2020 at 10:40:39AM -0400, Thomas Tai wrote: +++ b/include/linux/dma-direct.h @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, { dma_addr_t end = addr + size - 1;

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Christoph Hellwig
On Tue, Sep 15, 2020 at 10:40:39AM -0400, Thomas Tai wrote: >> +++ b/include/linux/dma-direct.h >> @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, >> dma_addr_t addr, size_t size, >> { >> dma_addr_t end = addr + size - 1; >> - if (!dev->dma_mask) >> -retu

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Thomas Tai
On 2020-09-15 10:26 a.m., Christoph Hellwig wrote: On Tue, Sep 15, 2020 at 10:11:51AM -0400, Thomas Tai wrote: On 2020-09-15 10:07 a.m., Christoph Hellwig wrote: On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: When booting the kernel v5.9-rc4 on a VM, the kernel would panic whe

Re: [PATCH] dma-direct: Fix potential NULL pointer dereference

2020-09-15 Thread Christoph Hellwig
On Tue, Sep 15, 2020 at 04:07:19PM +0200, Christoph Hellwig wrote: > On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: > > When booting the kernel v5.9-rc4 on a VM, the kernel would panic when > > printing a warning message in swiotlb_map(). It is because dev->dma_mask > > can potentially