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if we receive a compound such that: - the sessionid, slot, and sequence number in the SEQUENCE op match a cached succesful reply with N ops, and - the Nth operation of the compound is a PUTFH, PUTPUBFH, PUTROOTFH, or RESTOREFH, then nfsd4_sequence will return 0 and set cstate->status to nfserr_replay_cache. The current filehandle will not be set. This will cause us to call check_nfsd_access with first argument NULL. To nfsd4_compound it looks like we just succesfully executed an operation that set a filehandle, but the current filehandle is not set. Fix this by moving the nfserr_replay_cache earlier. There was never any reason to have it after the encode_op label, since the only case where he hit that is when opdesc->op_func sets it. Note that there are two ways we could hit this case: - a client is resending a previously sent compound that ended with one of the four PUTFH-like operations, or - a client is sending a *new* compound that (incorrectly) shares sessionid, slot, and sequence number with a previously sent compound, and the length of the previously sent compound happens to match the position of a PUTFH-like operation in the new compound. The second is obviously incorrect client behavior. The first is also very strange--the only purpose of a PUTFH-like operation is to set the current filehandle to be used by the following operation, so there's no point in having it as the last in a compound. So it's likely this requires a buggy or malicious client to reproduce. Reported-by: Scott Mayhew <smayhew@redhat.com> Cc: stable@kernel.vger.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.