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[68.48.65.54]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50e1b012b23sm3713071cf.30.2026.04.14.20.23.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 20:23:52 -0700 (PDT) From: Michael Bommarito To: linux-usb@vger.kernel.org, Mika Westerberg Cc: Andreas Noever , Yehezkel Bernat , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 2/2] thunderbolt: test: add KUnit regression tests for XDomain property parser Date: Tue, 14 Apr 2026 23:23:35 -0400 Message-ID: <20260415032335.2826412-3-michael.bommarito@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260415032335.2826412-1-michael.bommarito@gmail.com> References: <20260415032335.2826412-1-michael.bommarito@gmail.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add three KUnit cases that exercise the defects fixed by the parent commit by feeding crafted XDomain property blocks to tb_property_parse_dir(): tb_test_property_parse_u32_wrap - entry->value = 0xFFFFFF00 and entry->length = 0x100 so their u32 sum 0x100000000 wraps to 0 under the block_len guard; without the fix the subsequent parse_dwdata() reads attacker-directed OOB memory. tb_test_property_parse_recursion - two DIRECTORY entries pointing at each other, driving __tb_property_parse_dir() recursion; without the fix the kernel stack is exhausted. tb_test_property_parse_dir_len_underflow - a DIRECTORY entry with length < 4 so non-root content_len = dir_len - 4 wraps size_t; without the fix nentries is huge and the entry walk runs OOB. Each test asserts tb_property_parse_dir() returns NULL on the crafted input. With CONFIG_KASAN=y, running these on the pre-fix kernel reproduces an oops inside __tb_property_parse_dir (KASAN shadow-memory fault for the u32_wrap case, stack-guard trip for recursion, OOB read past block for dir_len underflow). Post-fix they pass cleanly. Run with: ./tools/testing/kunit/kunit.py run --arch=x86_64 \\ --kconfig_add CONFIG_PCI=y --kconfig_add CONFIG_NVMEM=y \\ --kconfig_add CONFIG_USB4=y --kconfig_add CONFIG_USB4_KUNIT_TEST=y \\ --kconfig_add CONFIG_KASAN=y 'thunderbolt.tb_test_property_parse_*' Assisted-by: Claude:claude-opus-4-6 Assisted-by: Codex:gpt-5-4 Signed-off-by: Michael Bommarito --- drivers/thunderbolt/test.c | 127 +++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) diff --git a/drivers/thunderbolt/test.c b/drivers/thunderbolt/test.c index 1f4318249c22..22f4107fcb8d 100644 --- a/drivers/thunderbolt/test.c +++ b/drivers/thunderbolt/test.c @@ -2852,7 +2852,134 @@ static void tb_test_property_copy(struct kunit *test) tb_property_free_dir(src); } +/* + * Reproducers for three memory-safety defects in + * drivers/thunderbolt/property.c reached from a crafted XDomain + * PROPERTIES_RESPONSE payload. Without the fix these trip KASAN or + * smash the kernel stack; with the fix each returns NULL cleanly. + */ +static void tb_test_property_parse_u32_wrap(struct kunit *test) +{ + u32 *block = kunit_kzalloc(test, 500 * sizeof(u32), GFP_KERNEL); + struct tb_property_dir *dir; + struct { + u32 key_hi, key_lo; + u16 length; + u8 reserved; + u8 type; + u32 value; + } *e; + + /* Root header: magic + length=6 (single entry body of 4 dwords + + * 2 slack, keeps walk within block[]). */ + block[0] = 0x55584401; + block[1] = 6; + + /* Crafted DATA entry at block[2..5]: value = 0xFFFFFF00 and + * length = 0x100 are u32/u16 such that the u32 sum 0x100000000 + * wraps to 0, passing the sum <= block_len guard even though + * the real offset is block + 0xFFFFFF00 * 4 (~16 GiB past the + * block). The subsequent parse_dwdata() at property.c:132 + * copies entry->length*4 = 1024 bytes from that wild address + * into a fresh kcalloc buffer. + */ + e = (void *)&block[2]; + e->key_hi = 0x61616161; + e->key_lo = 0x61616161; + e->length = 0x100; + e->type = 0x64; /* TB_PROPERTY_TYPE_DATA */ + e->value = 0xFFFFFF00; + + dir = tb_property_parse_dir(block, 500); + /* With the fix this returns NULL; without it, KASAN splats in + * be32_to_cpu_array() / memcpy reading block + value*4 out of + * bounds. Assert on the safe outcome: a NULL dir. */ + KUNIT_EXPECT_NULL(test, dir); + tb_property_free_dir(dir); +} + +static void tb_test_property_parse_recursion(struct kunit *test) +{ + u32 *block = kunit_kzalloc(test, 500 * sizeof(u32), GFP_KERNEL); + struct tb_property_dir *dir; + struct entry { + u32 key_hi, key_lo; + u16 length; + u8 reserved; + u8 type; + u32 value; + } *e, *child_e; + + block[0] = 0x55584401; + block[1] = 4; /* rootdir length = one entry */ + + /* DIRECTORY entry pointing at dir_offset=2 with length=16. + * When parsed as non-root: content_offset = 6, content_len = 12, + * nentries = 3. The child's first entry at block[6] is also + * DIRECTORY pointing at 2, so the recursion oscillates between + * two dir_offsets until the kernel stack is exhausted. + */ + e = (void *)&block[2]; + e->key_hi = 0x61616161; + e->key_lo = 0x61616161; + e->length = 16; + e->type = 0x44; /* TB_PROPERTY_TYPE_DIRECTORY */ + e->value = 2; + + child_e = (void *)&block[6]; + child_e->key_hi = 0x62626262; + child_e->key_lo = 0x62626262; + child_e->length = 16; + child_e->type = 0x44; + child_e->value = 2; + + dir = tb_property_parse_dir(block, 500); + /* With the fix this returns NULL at TB_PROPERTY_MAX_DEPTH (8). + * Without it, the kernel stack-guard fires ~50-80 frames in + * and the kunit thread oopses. */ + KUNIT_EXPECT_NULL(test, dir); + tb_property_free_dir(dir); +} + +static void tb_test_property_parse_dir_len_underflow(struct kunit *test) +{ + u32 *block = kunit_kzalloc(test, 500 * sizeof(u32), GFP_KERNEL); + struct tb_property_dir *dir; + struct entry { + u32 key_hi, key_lo; + u16 length; + u8 reserved; + u8 type; + u32 value; + } *e; + + block[0] = 0x55584401; + block[1] = 4; + + /* DIRECTORY entry with length=3. When parsed as non-root, + * content_len = dir_len - 4 underflows size_t to ~SIZE_MAX, + * nentries = SIZE_MAX/4. The for-loop walks entries past the + * block, reading OOB on each iteration. + */ + e = (void *)&block[2]; + e->key_hi = 0x61616161; + e->key_lo = 0x61616161; + e->length = 3; + e->type = 0x44; + e->value = 6; + + dir = tb_property_parse_dir(block, 500); + /* With the fix: NULL. Without: KASAN splat on + * block[content_offset + i*4] for i > 124 (past the 500-dword + * block). */ + KUNIT_EXPECT_NULL(test, dir); + tb_property_free_dir(dir); +} + static struct kunit_case tb_test_cases[] = { + KUNIT_CASE(tb_test_property_parse_u32_wrap), + KUNIT_CASE(tb_test_property_parse_recursion), + KUNIT_CASE(tb_test_property_parse_dir_len_underflow), KUNIT_CASE(tb_test_path_basic), KUNIT_CASE(tb_test_path_not_connected_walk), KUNIT_CASE(tb_test_path_single_hop_walk), -- 2.53.0