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-backlight | 186 ++++++++++++++++++++++++ 1 file changed, 186 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight (limited to 'Documentation/ABI/testing/sysfs-class-backlight') diff --git a/Documentation/ABI/testing/sysfs-class-backlight b/Documentation/ABI/testing/sysfs-class-backlight new file mode 100644 index 000000000..c453646b0 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-backlight @@ -0,0 +1,186 @@ +What: /sys/class/backlight//scale +Date: July 2019 +KernelVersion: 5.4 +Contact: Daniel Thompson +Description: + Description of the scale of the brightness curve. + + The human eye senses brightness approximately logarithmically, + hence linear changes in brightness are perceived as being + non-linear. To achieve a linear perception of brightness changes + controls like sliders need to apply a logarithmic mapping for + backlights with a linear brightness curve. + + Possible values of the attribute are: + + unknown + The scale of the brightness curve is unknown. + + linear + The brightness changes linearly with each step. Brightness + controls should apply a logarithmic mapping for a linear + perception. + + non-linear + The brightness changes non-linearly with each step. Brightness + controls should use a linear mapping for a linear perception. + +What: /sys/class/backlight//ambient_light_level +Date: Apr, 2010 +KernelVersion: v2.6.35 +Contact: Michael Hennerich +Description: + (RO) Get conversion value of the light sensor. + + The value is automatically updated every 80 ms when the + light sensor is enabled. + + The value range is device-driver specific: + + For ADP8870: + + It returns integer between 0 (dark) and 8000 (max ambient + brightness). + + For ADP8860: + + It returns a 13-bits integer. + +What: /sys/class/backlight//ambient_light_zone +Date: Apr, 2010 +KernelVersion: v2.6.35 +Contact: Michael Hennerich , + device-drivers-devel@blackfin.uclinux.org + +Description: + (RW) Read or write the specific brightness level at which the + backlight operates. + + The value meaning is device-driver specific: + + For ADP8860: + + == ========================== + 0 Off: Backlight set to 0 mA + 1 Level 1: daylight + 2 Level 2: bright + 3 Level 3: dark + == ========================== + + For ADP8870: + + == ========================== + 0 Off: Backlight set to 0 mA + 1 Level 1: daylight + 2 Level 2: bright + 3 Level 3: office + 4 Level 4: indoor + 5 Level 5: dark + == ========================== + + Writing 0 returns to normal/automatic ambient light level + operation. + + It can be enabled by writing the value stored in + /sys/class/backlight//max_brightness to + /sys/class/backlight//brightness. + +What: /sys/class/backlight//_max +Date: Sep, 2009 +KernelVersion: v2.6.32 +Contact: device-drivers-devel@blackfin.uclinux.org +Description: + Control the maximum brightness for + on this . Values are between 0 and 127. This file + will also show the brightness level stored for this + . + + The is device-driver specific: + + For ADP5520 and ADP5501, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + daylight /sys/class/backlight//daylight_max + office /sys/class/backlight//office_max + dark /sys/class/backlight//dark_max + =========== ================================================ + + For ADP8860, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_max + l2_office /sys/class/backlight//l2_office_max + l3_dark /sys/class/backlight//l3_dark_max + =========== ================================================ + + For ADP8870, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_max + l2_bright /sys/class/backlight//l2_bright_max + l3_office /sys/class/backlight//l3_office_max + l4_indoor /sys/class/backlight//l4_indoor_max + l5_dark /sys/class/backlight//l5_dark_max + =========== ================================================ + + See also: /sys/class/backlight//ambient_light_zone. + +What: /sys/class/backlight//_dim +Date: Sep, 2009 +KernelVersion: v2.6.32 +Contact: device-drivers-devel@blackfin.uclinux.org +Description: + Control the dim brightness for + on this . Values are between 0 and 127, typically + set to 0. Full off when the backlight is disabled. + This file will also show the dim brightness level stored for + this . + + The is device-driver specific: + + For ADP5520 and ADP5501, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + daylight /sys/class/backlight//daylight_dim + office /sys/class/backlight//office_dim + dark /sys/class/backlight//dark_dim + =========== ================================================ + + For ADP8860, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_dim + l2_office /sys/class/backlight//l2_office_dim + l3_dark /sys/class/backlight//l3_dark_dim + =========== ================================================ + + For ADP8870, can be: + + =========== ================================================ + Ambient sysfs entry + light zone + =========== ================================================ + l1_daylight /sys/class/backlight//l1_daylight_dim + l2_bright /sys/class/backlight//l2_bright_dim + l3_office /sys/class/backlight//l3_office_dim + l4_indoor /sys/class/backlight//l4_indoor_dim + l5_dark /sys/class/backlight//l5_dark_dim + =========== ================================================ + + See also: /sys/class/backlight//ambient_light_zone. + -- cgit v1.3.1