diff options
| author | Pierre-Yves MORDRET <pierre-yves.mordret@st.com> | 2018-03-13 17:55:35 +0100 |
|---|---|---|
| committer | Vinod Koul <vinod.koul@intel.com> | 2018-03-22 10:51:35 +0530 |
| commit | 3e4543bf20531d1cdb8672d25b3f2ff6d3d07627 (patch) | |
| tree | 0e4ccf921f0c9f47e68e0f242596302e212e35be | |
| parent | 0c8efd610b58cb23cefdfa12015799079aef94ae (diff) | |
dmaengine: stm32-dmamux: fix a potential buffer overflow
The bitfield dma_inuse is allocated of size dma_requests bits, thus a
valid bit address is from 0 to (dma_requests - 1).
When find_first_zero_bit() fails, it returns dma_requests as invalid
address.
Using such address for the following set_bit() is incorrect and, if
dma_requests is a multiple of BITS_PER_LONG, it will cause a buffer
overflow.
Currently this driver is only used in DT stm32h743.dtsi where a safe value
dma_requests=16 is not triggering the buffer overflow.
Fixed by checking the return value of find_first_zero_bit() _before_
using it.
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
| -rw-r--r-- | drivers/dma/stm32-dmamux.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c index 4dbb30cf94ac..b922db90939a 100644 --- a/drivers/dma/stm32-dmamux.c +++ b/drivers/dma/stm32-dmamux.c @@ -118,14 +118,15 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec, spin_lock_irqsave(&dmamux->lock, flags); mux->chan_id = find_first_zero_bit(dmamux->dma_inuse, dmamux->dma_requests); - set_bit(mux->chan_id, dmamux->dma_inuse); - spin_unlock_irqrestore(&dmamux->lock, flags); if (mux->chan_id == dmamux->dma_requests) { + spin_unlock_irqrestore(&dmamux->lock, flags); dev_err(&pdev->dev, "Run out of free DMA requests\n"); ret = -ENOMEM; - goto error; + goto error_chan_id; } + set_bit(mux->chan_id, dmamux->dma_inuse); + spin_unlock_irqrestore(&dmamux->lock, flags); /* Look for DMA Master */ for (i = 1, min = 0, max = dmamux->dma_reqs[i]; @@ -173,6 +174,8 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec, error: clear_bit(mux->chan_id, dmamux->dma_inuse); + +error_chan_id: kfree(mux); return ERR_PTR(ret); } |