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 --- drivers/accessibility/speakup/thread.c | 62 ++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 drivers/accessibility/speakup/thread.c (limited to 'drivers/accessibility/speakup/thread.c') diff --git a/drivers/accessibility/speakup/thread.c b/drivers/accessibility/speakup/thread.c new file mode 100644 index 000000000..2fc75e60f --- /dev/null +++ b/drivers/accessibility/speakup/thread.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#include "spk_types.h" +#include "speakup.h" +#include "spk_priv.h" + +DECLARE_WAIT_QUEUE_HEAD(speakup_event); +EXPORT_SYMBOL_GPL(speakup_event); + +int speakup_thread(void *data) +{ + unsigned long flags; + int should_break; + struct bleep our_sound; + + our_sound.active = 0; + our_sound.freq = 0; + our_sound.jiffies = 0; + + mutex_lock(&spk_mutex); + while (1) { + DEFINE_WAIT(wait); + + while (1) { + spin_lock_irqsave(&speakup_info.spinlock, flags); + our_sound = spk_unprocessed_sound; + spk_unprocessed_sound.active = 0; + prepare_to_wait(&speakup_event, &wait, + TASK_INTERRUPTIBLE); + should_break = kthread_should_stop() || + our_sound.active || + (synth && synth->catch_up && synth->alive && + (speakup_info.flushing || + !synth_buffer_empty())); + spin_unlock_irqrestore(&speakup_info.spinlock, flags); + if (should_break) + break; + mutex_unlock(&spk_mutex); + schedule(); + mutex_lock(&spk_mutex); + } + finish_wait(&speakup_event, &wait); + if (kthread_should_stop()) + break; + + if (our_sound.active) + kd_mksound(our_sound.freq, our_sound.jiffies); + if (synth && synth->catch_up && synth->alive) { + /* + * It is up to the callee to take the lock, so that it + * can sleep whenever it likes + */ + synth->catch_up(synth); + } + + speakup_start_ttys(); + } + mutex_unlock(&spk_mutex); + return 0; +} -- cgit v1.3.1