thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()

Overview

In the Linux kernel, the following vulnerability has been resolved:

thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()

entry->value is u32 and entry->length is u16; the sum is performed in u32 and wraps. A malicious XDomain peer can pick value = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0 and passes the > block_len check. tb_property_parse() then passes entry->value to parse_dwdata() as a dword offset into the property block, reading attacker-directed memory far past the allocation.

For TEXT-typed entries with the "deviceid" or "vendorid" keys this lands in xd->device_name / xd->vendor_name and is readable back via the per-XDomain device_name / vendor_name sysfs attributes; the leak is NUL-bounded (kstrdup() stops at the first zero byte) and untargeted (the attacker picks a delta, not an absolute address). DATA-typed entries are parsed into property->value.data but not generically surfaced to userspace.

Use check_add_overflow() so a wrapped sum is rejected.

Affected

• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 6a63623621639acbb39bc2d9fb09559681716695
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 9fee50c4e1e42f6d3cbe30df584f9f648f626071
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 8d4a758b407ab3de3be86d1ceadfa35d717d30c7
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 5c06a3043ad944f087bb2ae0aae28d820bb9f460
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 31b98e503ecca8077e5247253dd5425ab84bc96d
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < a47784aee77f33f786dc5d7375db821bdae68792
• Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 01deda0152066c6c955f0619114ea6afa070aaec
• Linux 4.15

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.