From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- Documentation/ABI/testing/procfs-diskstats | 43 ++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 Documentation/ABI/testing/procfs-diskstats (limited to 'Documentation/ABI/testing/procfs-diskstats') diff --git a/Documentation/ABI/testing/procfs-diskstats b/Documentation/ABI/testing/procfs-diskstats new file mode 100644 index 000000000..6a719cf20 --- /dev/null +++ b/Documentation/ABI/testing/procfs-diskstats @@ -0,0 +1,43 @@ +What: /proc/diskstats +Date: February 2008 +Contact: Jerome Marchand +Description: + The /proc/diskstats file displays the I/O statistics + of block devices. Each line contains the following 14 + fields: + + == =================================== + 1 major number + 2 minor number + 3 device name + 4 reads completed successfully + 5 reads merged + 6 sectors read + 7 time spent reading (ms) + 8 writes completed + 9 writes merged + 10 sectors written + 11 time spent writing (ms) + 12 I/Os currently in progress + 13 time spent doing I/Os (ms) + 14 weighted time spent doing I/Os (ms) + == =================================== + + Kernel 4.18+ appends four more fields for discard + tracking putting the total at 18: + + == =================================== + 15 discards completed successfully + 16 discards merged + 17 sectors discarded + 18 time spent discarding + == =================================== + + Kernel 5.5+ appends two more fields for flush requests: + + == ===================================== + 19 flush requests completed successfully + 20 time spent flushing + == ===================================== + + For more details refer to Documentation/admin-guide/iostats.rst -- cgit v1.3.1