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 --- samples/watchdog/.gitignore | 2 ++ samples/watchdog/Makefile | 2 ++ samples/watchdog/watchdog-simple.c | 25 +++++++++++++++++++++++++ 3 files changed, 29 insertions(+) create mode 100644 samples/watchdog/.gitignore create mode 100644 samples/watchdog/Makefile create mode 100644 samples/watchdog/watchdog-simple.c (limited to 'samples/watchdog') diff --git a/samples/watchdog/.gitignore b/samples/watchdog/.gitignore new file mode 100644 index 000000000..a70a0150e --- /dev/null +++ b/samples/watchdog/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +/watchdog-simple diff --git a/samples/watchdog/Makefile b/samples/watchdog/Makefile new file mode 100644 index 000000000..ab39d23dc --- /dev/null +++ b/samples/watchdog/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0 +userprogs-always-y += watchdog-simple diff --git a/samples/watchdog/watchdog-simple.c b/samples/watchdog/watchdog-simple.c new file mode 100644 index 000000000..9ce66d2ca --- /dev/null +++ b/samples/watchdog/watchdog-simple.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include + +int main(void) +{ + int fd = open("/dev/watchdog", O_WRONLY); + int ret = 0; + if (fd == -1) { + perror("watchdog"); + exit(EXIT_FAILURE); + } + while (1) { + ret = write(fd, "\0", 1); + if (ret != 1) { + ret = -1; + break; + } + sleep(10); + } + close(fd); + return ret; +} -- cgit v1.3.1