tree b892c5ef2dd2353c0c53b613d01162cb1c427352
parent a1f26739ccdcc6967617998bd200dd907f7ff80a
author Chuck Lever <chuck.lever@oracle.com> 1607470142 -0500
committer Trond Myklebust <trond.myklebust@hammerspace.com> 1607946667 -0500

xprtrdma: Fix XDRBUF_SPARSE_PAGES support

Olga K. observed that rpcrdma_marsh_req() allocates sparse pages
only when it has determined that a Reply chunk is necessary. There
are plenty of cases where no Reply chunk is needed, but the
XDRBUF_SPARSE_PAGES flag is set. The result would be a crash in
rpcrdma_inline_fixup() when it tries to copy parts of the received
Reply into a missing page.

To avoid crashing, handle sparse page allocation up front.

Until XATTR support was added, this issue did not appear often
because the only SPARSE_PAGES consumer always expected a reply large
enough to always require a Reply chunk.

Reported-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>