CVE-2026-31708 PUBLISHED

smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path

Assigner: Linux
Reserved: 09.03.2026 Published: 01.05.2026 Updated: 01.05.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from f5778c398713692a16150ae96e5c8270bab8399f to a34d456934fe42e4da5d2cc07787bf418bee99c6 (excl.)
  • affected from f5778c398713692a16150ae96e5c8270bab8399f to ac2f14e4705d020f04e806efa0d49ab8dc2b145f (excl.)
  • affected from f5778c398713692a16150ae96e5c8270bab8399f to 078fae8f50adebb903ccf2252b44391324571e78 (excl.)
  • affected from f5778c398713692a16150ae96e5c8270bab8399f to 85fd46ee26a11841c670449508025965f61ce131 (excl.)
  • affected from f5778c398713692a16150ae96e5c8270bab8399f to a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 5.1 is affected
  • unaffected from 0 to 5.1 (excl.)
  • unaffected from 6.6.136 to 6.6.* (incl.)
  • unaffected from 6.12.84 to 6.12.* (incl.)
  • unaffected from 6.18.25 to 6.18.* (incl.)
  • unaffected from 7.0.2 to 7.0.* (incl.)
  • unaffected from 7.1-rc1 to * (incl.)

References