Re: [PATCH v2] dma-mapping: Use dma_get_mask in dma_addressing_limited
From: Auger Eric <eric.auger@redhat.com>
Date: 2019-07-22 16:56:49
Hi Christoph, On 7/22/19 6:51 PM, Eric Auger wrote:
We currently have cases where the dma_addressing_limited() gets
called with dma_mask unset. This causes a NULL pointer dereference.
Use dma_get_mask() accessor to prevent the crash.
Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper")
Signed-off-by: Eric Auger <eric.auger@redhat.com>As a follow-up of my last email, here is a patch featuring dma_get_mask(). But you don't have the WARN_ON_ONCE anymore, pointing out suspect users. Feel free to pick up your preferred approach Thanks Eric
quoted hunk
--- v1 -> v2: - was [PATCH 1/2] dma-mapping: Protect dma_addressing_limited against NULL dma_mask - Use dma_get_mask --- include/linux/dma-mapping.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index e11b115dd0e4..f7d1eea32c78 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h@@ -689,8 +689,8 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask) */ static inline bool dma_addressing_limited(struct device *dev) { - return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < - dma_get_required_mask(dev); + return min_not_zero(dma_get_mask(dev), dev->bus_dma_mask) < + dma_get_required_mask(dev); } #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS