CVE-2026-99272

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

smb: client: validate the data area in SMB2 read()

SMB2 read() copies le32 to cpu(rsp->DataLength) bytes from (char *)rsp + rsp->DataOffset without checking that the range lies within the response actually received. A READ response with DataOffset == 0 makes smb2 get data area len() zero the data length, so smb2 check message() accepts a frame as short as the fixed response, while SMB2 read() still uses the server-supplied DataLength, capped only by CIFS MAX MSGSIZE and the caller's length.

A malicious server can answer the synchronous read used by the mfsymlinks (or SFU) symlink parser with an 81-byte READ response carrying DataOffset 0 and DataLength 1067, making the client copy 1067 bytes from a 448-byte receive object (KASAN slab-out-of-bounds; up to 16 KiB in the general case).

Clamp a zero (or header-overlapping) DataOffset to read rsp size, as handle read data() does for the asynchronous path, and reject the response unless DataOffset + DataLength fits within rsp iov.iov len. The SMB1 helper was fixed the same way in 5be5bdda5863.