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authorPierre-Yves MORDRET <pierre-yves.mordret@st.com>2018-03-13 17:55:35 +0100
committerVinod Koul <vinod.koul@intel.com>2018-03-22 10:51:35 +0530
commit3e4543bf20531d1cdb8672d25b3f2ff6d3d07627 (patch)
tree0e4ccf921f0c9f47e68e0f242596302e212e35be
parent0c8efd610b58cb23cefdfa12015799079aef94ae (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.c9
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);
}