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/crypto/tests/test-utils.h | 111 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 111 insertions(+) create mode 100644 lib/crypto/tests/test-utils.h (limited to 'lib/crypto/tests/test-utils.h') diff --git a/lib/crypto/tests/test-utils.h b/lib/crypto/tests/test-utils.h new file mode 100644 index 000000000..73ca21f91 --- /dev/null +++ b/lib/crypto/tests/test-utils.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Test utility functions shared by the crypto library tests. + * + * For now this is simply a header that's included into the KUnit test suites + * that need it. If this gets too large it could be made its own translation + * unit and libcrypto_test_utils module, but that seems overkill for now. + */ +#ifndef LIB_CRYPTO_TEST_UTILS_H +#define LIB_CRYPTO_TEST_UTILS_H + +#include +#include +#include +#include +#include + +static u64 random_seed; + +static __maybe_unused void action_free_guarded_buf(void *buf) +{ + vfree(buf); +} + +/* + * Allocate a KUnit-managed buffer that has length @size bytes (> 0) immediately + * followed by an unmapped page, and assert that the allocation succeeds. + */ +static __maybe_unused void *alloc_guarded_buf(struct kunit *test, size_t size) +{ + size_t full_size = round_up(size, PAGE_SIZE); + void *buf = vmalloc(full_size); + + KUNIT_ASSERT_NOT_NULL(test, buf); + KUNIT_ASSERT_EQ(test, 0, + kunit_add_action_or_reset(test, action_free_guarded_buf, + buf)); + return buf + full_size - size; +} + +static __maybe_unused void *alloc_buf(struct kunit *test, size_t size) +{ + void *buf = kunit_kmalloc(test, size, GFP_KERNEL); + + KUNIT_ASSERT_NOT_NULL(test, buf); + return buf; +} + +static __maybe_unused void *memdup_buf(struct kunit *test, const void *src, + size_t size) +{ + void *dst = alloc_buf(test, size); + + return memcpy(dst, src, size); +} + +/* + * This is a simple linear congruential generator. It is used only for testing, + * which does not require cryptographically secure random numbers. A hard-coded + * algorithm is used instead of so that it matches the + * algorithm used by the test vector generation script. This allows the input + * data in random test vectors to be concisely stored as just the seed. + */ +static __maybe_unused u32 rand32(void) +{ + random_seed = (random_seed * 25214903917 + 11) & ((1ULL << 48) - 1); + return random_seed >> 16; +} + +static __maybe_unused void rand_bytes(u8 *out, size_t len) +{ + for (size_t i = 0; i < len; i++) + out[i] = rand32(); +} + +static __maybe_unused void rand_bytes_seeded_from_len(u8 *out, size_t len) +{ + random_seed = len; + rand_bytes(out, len); +} + +static __maybe_unused bool rand_bool(void) +{ + return rand32() % 2; +} + +/* Generate a random length, preferring small lengths. */ +static __maybe_unused size_t rand_length(size_t max_len) +{ + size_t len; + + switch (rand32() % 3) { + case 0: + len = rand32() % 128; + break; + case 1: + len = rand32() % 3072; + break; + default: + len = rand32(); + break; + } + return len % (max_len + 1); +} + +static __maybe_unused size_t rand_offset(size_t max_offset) +{ + return min(rand32() % 128, max_offset); +} + +#endif /* LIB_CRYPTO_TEST_UTILS_H */ -- cgit v1.3.1