From de21b59c29e31c5108ddc04210631bbfab81b997 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Sun, 10 May 2026 19:16:57 -0400 Subject: [PATCH] thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow On the non-root path, __tb_property_parse_dir() takes dir_len from entry->length (u16 widened to size_t). Two distinct OOB conditions follow when entry->length < 4: 1. The non-root path begins with kmemdup(&block[dir_offset], sizeof(*dir->uuid), ...) which always reads 4 dwords from dir_offset. tb_property_entry_valid() only enforces dir_offset + entry->length <= block_len, so a crafted entry with dir_offset close to the end of the property block and entry->length in 0..3 passes that gate but lets the UUID copy run off the block (e.g. dir_offset = 497, dir_len = 3 in a 500-dword block reads block[497..501]). 2. After the kmemdup, content_len = dir_len - 4 underflows size_t to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry walk runs OOB on each iteration until an entry fails validation or the kernel oopses on an unmapped page. Reject dir_len < 4 on the non-root path *before* the UUID kmemdup, which closes both holes. Also move INIT_LIST_HEAD(&dir->properties) up to immediately after the dir allocation so the new error-return path (and the existing uuid-alloc failure path) calling tb_property_free_dir() sees a walkable list rather than the zero-initialized NULL next/prev that list_for_each_entry_safe() would oops on. Fixes: cdae7c07e3e3 ("thunderbolt: Add support for XDomain properties") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-6 Assisted-by: Codex:gpt-5-4 Signed-off-by: Michael Bommarito Signed-off-by: Mika Westerberg --- drivers/thunderbolt/property.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c index 29cd60c11ac4..74c92f9801ff 100644 --- a/drivers/thunderbolt/property.c +++ b/drivers/thunderbolt/property.c @@ -174,10 +174,16 @@ static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, if (!dir) return NULL; + INIT_LIST_HEAD(&dir->properties); + if (is_root) { content_offset = dir_offset + 2; content_len = dir_len; } else { + if (dir_len < 4) { + tb_property_free_dir(dir); + return NULL; + } dir->uuid = kmemdup(&block[dir_offset], sizeof(*dir->uuid), GFP_KERNEL); if (!dir->uuid) { @@ -191,8 +197,6 @@ static struct tb_property_dir *__tb_property_parse_dir(const u32 *block, entries = (const struct tb_property_entry *)&block[content_offset]; nentries = content_len / (sizeof(*entries) / 4); - INIT_LIST_HEAD(&dir->properties); - for (i = 0; i < nentries; i++) { struct tb_property *property;