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[68.48.65.54]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8fc2938e0b9sm766261985a.9.2026.05.03.07.15.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 03 May 2026 07:15:32 -0700 (PDT) From: Michael Bommarito To: Mika Westerberg , linux-usb@vger.kernel.org Cc: Andreas Noever , Yehezkel Bernat , Andy Shevchenko , Michael Jamet , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v3 4/4] thunderbolt: test: add KUnit regression tests for XDomain property parser Date: Sun, 3 May 2026 10:15:08 -0400 Message-ID: <5caddc2abbec9d4215dfc9041ab18f84eb7bbc58.1777817011.git.michael.bommarito@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260415123221.225149-1-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 sibling commits in this series 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 the non-root UUID kmemdup of 4 dwords from dir_offset reads past the block, and the downstream content_len = dir_len - 4 size_t underflow drives the entry walk OOB. Each test asserts tb_property_parse_dir() returns NULL on the crafted input. On a pre-fix kernel with CONFIG_KASAN=y, u32_wrap trips a KASAN report inside __tb_property_parse_dir() (the parser reads ~16 GiB past the block) and recursion trips an Oops on RIP=0 via the stack-guard. dir_len_underflow returns NULL on pre-fix via the downstream content_len underflow path; the UUID kmemdup over-read happens silently because KASAN-Generic's slab redzones do not flag a 4-byte over-read into the kmalloc-chunk tail, so this case is the post-fix invariant pin rather than an active pre-fix detector. Post-fix all three 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 --- v2 -> v3: - De-duplicate the on-wire entry layout: define a single struct tb_test_property_entry shared across all three tests instead of re-declaring an anonymous struct in each. - Use TB_PROPERTY_TYPE_DATA / TB_PROPERTY_TYPE_DIRECTORY constants from instead of bare 0x64 / 0x44. - Convert all multi-line block comments to put the opening "/*" on its own line per the thunderbolt subsystem's coding style. - Lowercase 0xffffff00 in commit message + code + comments. - Tighten dir_len_underflow: use a 7-dword (28-byte) buffer so the non-root kmemdup over-read targets the kmalloc-32 tail rather than slab slop within a kmalloc-2048 chunk. KASAN- Generic still does not flag the 4-byte over-read here (slab redzones cover next-chunk metadata, not in-chunk tail), so the test remains a post-fix invariant pin; documented explicitly above. drivers/thunderbolt/test.c | 132 +++++++++++++++++++++++++++++++++++++ 1 file changed, 132 insertions(+) diff --git a/drivers/thunderbolt/test.c b/drivers/thunderbolt/test.c index 1f4318249c22..73de7292ee21 100644 --- a/drivers/thunderbolt/test.c +++ b/drivers/thunderbolt/test.c @@ -2852,7 +2852,139 @@ 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. + * + * The on-wire entry layout mirrors struct tb_property_entry in + * property.c (private to that translation unit). + */ +struct tb_test_property_entry { + u32 key_hi, key_lo; + u16 length; + u8 reserved; + u8 type; + u32 value; +}; + +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 tb_test_property_entry *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() 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 = TB_PROPERTY_TYPE_DATA; + e->value = 0xffffff00; + + dir = tb_property_parse_dir(block, 500); + 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 tb_test_property_entry *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 = 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 = TB_PROPERTY_TYPE_DIRECTORY; + child_e->value = 2; + + dir = tb_property_parse_dir(block, 500); + KUNIT_EXPECT_NULL(test, dir); + tb_property_free_dir(dir); +} + +static void tb_test_property_parse_dir_len_underflow(struct kunit *test) +{ + /* + * Request 28 bytes (7 dwords) so KASAN-Generic tags the + * 4 trailing bytes of the underlying kmalloc-32 chunk as a + * slab redzone. With block_len=7, dir_offset=4, dir_len=3, + * the non-root UUID kmemdup reads 16 bytes from byte 16, so + * bytes 28..31 fall in the redzone and trip a KASAN + * slab-out-of-bounds report on the pre-fix kernel. Sizing + * the buffer at a power of two (32, 64, ... bytes) puts the + * over-read into the slab cache tail where KASAN's generic + * shadow does not flag it, and the test reduces to a + * tautology because the downstream content_len = dir_len - 4 + * underflow also returns NULL. + */ + u32 *block = kunit_kzalloc(test, 7 * sizeof(u32), GFP_KERNEL); + struct tb_property_dir *dir; + struct tb_test_property_entry *e; + + block[0] = 0x55584401; + block[1] = 4; /* rootdir length = one entry */ + + /* + * DIRECTORY entry with length=3 pointing at dir_offset=4. + * tb_property_entry_valid() permits value+length=7 <= + * block_len=7. Non-root parse begins with a kmemdup of 4 + * dwords from dir_offset for the UUID; with the v2 ordering + * that kmemdup runs before the dir_len < 4 reject and reads + * past the buffer. With the v3 ordering the reject sits + * before the kmemdup and the read never happens. + */ + e = (void *)&block[2]; + e->key_hi = 0x61616161; + e->key_lo = 0x61616161; + e->length = 3; + e->type = TB_PROPERTY_TYPE_DIRECTORY; + e->value = 4; + + dir = tb_property_parse_dir(block, 7); + 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