CVE-2026-31708

Summary

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

smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path

smb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL and the default QUERY_INFO path. The QUERY_INFO branch clamps qi.input_buffer_length to the server-reported OutputBufferLength and then copies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but it never verifies that the flexible-array payload actually fits within rsp_iov[1].iov_len.

A malicious server can return OutputBufferLength larger than the actual QUERY_INFO response, causing copy_to_user() to walk past the response buffer and expose adjacent kernel heap to userspace.

Guard the QUERY_INFO copy with a bounds check on the actual Buffer payload. Use struct_size(qi_rsp, Buffer, qi.input_buffer_length) rather than an open-coded addition so the guard cannot overflow on 32-bit builds.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e66bdc0704977ecee667a81d38255b579c2353d0
• https://git.kernel.org/stable/c/9e203dbb5402897c43130fb171a2617008a91f45
• https://git.kernel.org/stable/c/1dd757379997b71a328a4b591ffaf481acd0ead1
• https://git.kernel.org/stable/c/a34d456934fe42e4da5d2cc07787bf418bee99c6
• https://git.kernel.org/stable/c/ac2f14e4705d020f04e806efa0d49ab8dc2b145f
• https://git.kernel.org/stable/c/078fae8f50adebb903ccf2252b44391324571e78
• https://git.kernel.org/stable/c/85fd46ee26a11841c670449508025965f61ce131
• https://git.kernel.org/stable/c/a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e

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