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/md/dm-vdo/string-utils.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 drivers/md/dm-vdo/string-utils.c (limited to 'drivers/md/dm-vdo/string-utils.c') diff --git a/drivers/md/dm-vdo/string-utils.c b/drivers/md/dm-vdo/string-utils.c new file mode 100644 index 000000000..71e44b468 --- /dev/null +++ b/drivers/md/dm-vdo/string-utils.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2023 Red Hat + */ + +#include "string-utils.h" + +char *vdo_append_to_buffer(char *buffer, char *buf_end, const char *fmt, ...) +{ + va_list args; + size_t n; + + va_start(args, fmt); + n = vsnprintf(buffer, buf_end - buffer, fmt, args); + if (n >= (size_t) (buf_end - buffer)) + buffer = buf_end; + else + buffer += n; + va_end(args); + + return buffer; +} -- cgit v1.3.1