5.10-stable review patch. If anyone has any objections, please let me know.
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From: Amelie Delaunay amelie.delaunay@foss.st.com
[ Upstream commit f5c24d94512f1b288262beda4d3dcb9629222fc7 ]
__dma_async_device_channel_register() can fail. In case of failure, chan->local is freed (with free_percpu()), and chan->local is nullified. When dma_async_device_unregister() is called (because of managed API or intentionally by DMA controller driver), channels are unconditionally unregistered, leading to this NULL pointer: [ 1.318693] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000d0 [...] [ 1.484499] Call trace: [ 1.486930] device_del+0x40/0x394 [ 1.490314] device_unregister+0x20/0x7c [ 1.494220] __dma_async_device_channel_unregister+0x68/0xc0
Look at dma_async_device_register() function error path, channel device unregistration is done only if chan->local is not NULL.
Then add the same condition at the beginning of __dma_async_device_channel_unregister() function, to avoid NULL pointer issue whatever the API used to reach this function.
Fixes: d2fb0a043838 ("dmaengine: break out channel registration") Signed-off-by: Amelie Delaunay amelie.delaunay@foss.st.com Reviewed-by: Dave Jiang dave.jiang@intel.com Link: https://lore.kernel.org/r/20231213160452.2598073-1-amelie.delaunay@foss.st.c... Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/dmaengine.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 4ec7bb58c195..9559ebd61f3b 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -1108,6 +1108,9 @@ EXPORT_SYMBOL_GPL(dma_async_device_channel_register); static void __dma_async_device_channel_unregister(struct dma_device *device, struct dma_chan *chan) { + if (chan->local == NULL) + return; + WARN_ONCE(!device->device_release && chan->client_count, "%s called while %d clients hold a reference\n", __func__, chan->client_count);