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 --- lib/debug_locks.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 lib/debug_locks.c (limited to 'lib/debug_locks.c') diff --git a/lib/debug_locks.c b/lib/debug_locks.c new file mode 100644 index 000000000..a75ee30b7 --- /dev/null +++ b/lib/debug_locks.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * lib/debug_locks.c + * + * Generic place for common debugging facilities for various locks: + * spinlocks, rwlocks, mutexes and rwsems. + * + * Started by Ingo Molnar: + * + * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar + */ +#include +#include +#include +#include +#include + +/* + * We want to turn all lock-debugging facilities on/off at once, + * via a global flag. The reason is that once a single bug has been + * detected and reported, there might be cascade of followup bugs + * that would just muddy the log. So we report the first one and + * shut up after that. + */ +int debug_locks __read_mostly = 1; +EXPORT_SYMBOL_GPL(debug_locks); + +/* + * The locking-testsuite uses to get a + * 'silent failure': nothing is printed to the console when + * a locking bug is detected. + */ +int debug_locks_silent __read_mostly; +EXPORT_SYMBOL_GPL(debug_locks_silent); + +/* + * Generic 'turn off all lock debugging' function: + */ +int debug_locks_off(void) +{ + if (debug_locks && __debug_locks_off()) { + if (!debug_locks_silent) { + console_verbose(); + return 1; + } + } + return 0; +} +EXPORT_SYMBOL_GPL(debug_locks_off); -- cgit v1.3.1