smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr() reparse_buf_ptr() reads buf->ReparseDataLength before checking that count covers the full fixed header: buf = (struct reparse_data_buffer *)((u8 *)io + off); len = sizeof(*buf); /* 8 bytes */ rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */ if (count < len || count < rdlen + len) /* check comes after */ struct reparse_data_buffer has ReparseDataLength at offset 4. If a server returns OutputCount < 6, the read at offset 4-5 reaches past the end of the received data. The off+count bounds against iov_len were already validated, but that does not protect against count being smaller than sizeof(*buf). Split the check: verify count >= sizeof(*buf) before reading ReparseDataLength, then verify count covers the data region.

Source published

11 Sep 2026 19:45:27 UTC

Source modified

21 Oct 2026 12:48:04 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H