We already dereferenced "dev" when we called get_dma_ops() so this NULL check is too late. We're not supposed to pass NULL "dev" pointers to dma_alloc_attrs().
Signed-off-by: Dan Carpenter <[email protected]> --- There are still at least two drivers which do pass a NULL unfortunately. drivers/staging/comedi/drivers/comedi_isadma.c:195 comedi_isadma_alloc() error: NULL dereference inside function 'dma_alloc_coherent()' drivers/staging/comedi/drivers/comedi_isadma.c:227 comedi_isadma_free() error: NULL dereference inside function 'dma_free_coherent()' drivers/tty/synclink.c:3667 mgsl_alloc_buffer_list_memory() error: NULL dereference inside function 'dma_alloc_coherent()' drivers/tty/synclink.c:3738 mgsl_free_buffer_list_memory() error: NULL dereference inside function 'dma_free_coherent()' drivers/tty/synclink.c:3777 mgsl_alloc_frame_memory() error: NULL dereference inside function 'dma_alloc_coherent()' drivers/tty/synclink.c:3811 mgsl_free_frame_memory() error: NULL dereference inside function 'dma_free_coherent()' If I remember right there are one or two others which sometimes pass a NULL, but it's harder to grep for those warnings. kernel/dma/mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 685a53f2a793..f7afdadb6770 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -244,7 +244,7 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, const struct dma_map_ops *ops = get_dma_ops(dev); void *cpu_addr; - WARN_ON_ONCE(dev && !dev->coherent_dma_mask); + WARN_ON_ONCE(!dev->coherent_dma_mask); if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr)) return cpu_addr; -- 2.18.0 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
