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/sysfs-class-rnbd-server | 58 +++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-rnbd-server (limited to 'Documentation/ABI/testing/sysfs-class-rnbd-server') diff --git a/Documentation/ABI/testing/sysfs-class-rnbd-server b/Documentation/ABI/testing/sysfs-class-rnbd-server new file mode 100644 index 000000000..6c5996cd7 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-rnbd-server @@ -0,0 +1,58 @@ +What: /sys/class/rnbd-server +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: provide information about RNBD-server. + +What: /sys/class/rnbd-server/ctl/ +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: When a client maps a device, a directory entry with the name of the + block device is created under /sys/class/rnbd-server/ctl/devices/. + +What: /sys/class/rnbd-server/ctl/devices//block_dev +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Is a symlink to the sysfs entry of the exported device. + + Example: + block_dev -> ../../../../class/block/ram0 + +What: /sys/class/rnbd-server/ctl/devices//sessions/ +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: For each client a particular device is exported to, following directory will be + created: + + /sys/class/rnbd-server/ctl/devices//sessions// + + When the device is unmapped by that client, the directory will be removed. + +What: /sys/class/rnbd-server/ctl/devices//sessions//read_only +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains '1' if device is mapped read-only, otherwise '0'. + +What: /sys/class/rnbd-server/ctl/devices//sessions//mapping_path +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the relative device path provided by the user during mapping. + +What: /sys/class/rnbd-server/ctl/devices//sessions//access_mode +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang Danil Kipnis +Description: Contains the device access mode: ro, rw or migration. + +What: /sys/class/rnbd-server/ctl/devices//sessions//force_close +Date: Nov 2020 +KernelVersion: 5.10 +Contact: Jack Wang Danil Kipnis +Description: Write "1" to the file to close the device on server side. Please + note that the client side device will not be closed, read or + write to the device will get -ENOTCONN. -- cgit v1.3.1