ksmbd: prevent out-of-bounds stream writes by validating *pos

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent out-of-bounds stream writes by validating *pos ksmbd_vfs_stream_write() did not validate whether the write offset (*pos) was within the bounds of the existing stream data length (v_len). If *pos was greater than or equal to v_len, this could lead to an out-of-bounds memory write. This patch adds a check to ensure *pos is less than v_len before proceeding. If the condition fails, -EINVAL is returned.

References

• https://git.kernel.org/stable/c/7f61da79df86fd140c7768e668ad846bfa7ec8e1
• https://git.kernel.org/stable/c/04c8a38c60346bb5a7c49b276de7233f703ce9cb
• https://git.kernel.org/stable/c/d62ba16563a86aae052f96d270b3b6f78fca154c
• https://git.kernel.org/stable/c/e6356499fd216ed6343ae0363f4c9303f02c5034
• https://git.kernel.org/stable/c/0ca6df4f40cf4c32487944aaf48319cb6c25accc