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 --- include/kunit/skbuff.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 include/kunit/skbuff.h (limited to 'include/kunit/skbuff.h') diff --git a/include/kunit/skbuff.h b/include/kunit/skbuff.h new file mode 100644 index 000000000..077846943 --- /dev/null +++ b/include/kunit/skbuff.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KUnit resource management helpers for SKBs (skbuff). + * + * Copyright (C) 2023 Intel Corporation + */ + +#ifndef _KUNIT_SKBUFF_H +#define _KUNIT_SKBUFF_H + +#include +#include + +static void kunit_action_kfree_skb(void *p) +{ + kfree_skb((struct sk_buff *)p); +} + +/** + * kunit_zalloc_skb() - Allocate and initialize a resource managed skb. + * @test: The test case to which the skb belongs + * @len: size to allocate + * @gfp: allocation flags + * + * Allocate a new struct sk_buff with gfp flags, zero fill the given length + * and add it as a resource to the kunit test for automatic cleanup. + * + * Returns: newly allocated SKB, or %NULL on error + */ +static inline struct sk_buff *kunit_zalloc_skb(struct kunit *test, int len, + gfp_t gfp) +{ + struct sk_buff *res = alloc_skb(len, gfp); + + if (!res || skb_pad(res, len)) + return NULL; + + if (kunit_add_action_or_reset(test, kunit_action_kfree_skb, res)) + return NULL; + + return res; +} + +/** + * kunit_kfree_skb() - Like kfree_skb except for allocations managed by KUnit. + * @test: The test case to which the resource belongs. + * @skb: The SKB to free. + */ +static inline void kunit_kfree_skb(struct kunit *test, struct sk_buff *skb) +{ + if (!skb) + return; + + kunit_release_action(test, kunit_action_kfree_skb, (void *)skb); +} + +#endif /* _KUNIT_SKBUFF_H */ -- cgit v1.3.1