Author: dfr
Date: Sun May 24 13:22:00 2009
New Revision: 192686
URL: http://svn.freebsd.org/changeset/base/192686
Log:
Make sure we feed 32bit align memory to nfsm_dissect otherwise we will fault
on platforms with strict alignment requirements. In particular, this fixes the
problems with the new RPC transport on the arm platform.
Note: this adds yet another copy of nfs_realign(). I will attempt to refactor
after NFS_LEGACYRPC is removed.
Submitted by: sam
Modified:
head/sys/nfsclient/nfs_krpc.c
Modified: head/sys/nfsclient/nfs_krpc.c
==============================================================================
--- head/sys/nfsclient/nfs_krpc.c Sun May 24 12:39:38 2009
(r192685)
+++ head/sys/nfsclient/nfs_krpc.c Sun May 24 13:22:00 2009
(r192686)
@@ -407,6 +407,65 @@ nfs_feedback(int type, int proc, void *a
}
/*
+ * nfs_realign:
+ *
+ * Check for badly aligned mbuf data and realign by copying the unaligned
+ * portion of the data into a new mbuf chain and freeing the portions
+ * of the old chain that were replaced.
+ *
+ * We cannot simply realign the data within the existing mbuf chain
+ * because the underlying buffers may contain other rpc commands and
+ * we cannot afford to overwrite them.
+ *
+ * We would prefer to avoid this situation entirely. The situation does
+ * not occur with NFS/UDP and is supposed to only occassionally occur
+ * with TCP. Use vfs.nfs.realign_count and realign_test to check this.
+ *
+ */
+static int
+nfs_realign(struct mbuf **pm, int hsiz)
+{
+ struct mbuf *m, *n;
+ int off, space;
+
+ ++nfs_realign_test;
+ while ((m = *pm) != NULL) {
+ if ((m->m_len & 0x3) || (mtod(m, intptr_t) & 0x3)) {
+ /*
+ * NB: we can't depend on m_pkthdr.len to help us
+ * decide what to do here. May not be worth doing
+ * the m_length calculation as m_copyback will
+ * expand the mbuf chain below as needed.
+ */
+ space = m_length(m, NULL);
+ if (space >= MINCLSIZE) {
+ /* NB: m_copyback handles space > MCLBYTES */
+ n = m_getcl(M_DONTWAIT, MT_DATA, 0);
+ } else
+ n = m_get(M_DONTWAIT, MT_DATA);
+ if (n == NULL)
+ return (ENOMEM);
+ /*
+ * Align the remainder of the mbuf chain.
+ */
+ n->m_len = 0;
+ off = 0;
+ while (m != NULL) {
+ m_copyback(n, off, m->m_len, mtod(m, caddr_t));
+ off += m->m_len;
+ m = m->m_next;
+ }
+ m_freem(*pm);
+ *pm = n;
+ ++nfs_realign_count;
+ break;
+ }
+ pm = &m->m_next;
+ }
+ return (0);
+}
+
+/*
* nfs_request - goes something like this
* - fill in request struct
* - links it into list
@@ -525,12 +584,25 @@ tryagain:
} else {
error = EACCES;
}
- md = mrep;
if (error)
goto nfsmout;
KASSERT(mrep != NULL, ("mrep shouldn't be NULL if no error\n"));
+ /*
+ * Search for any mbufs that are not a multiple of 4 bytes long
+ * or with m_data not longword aligned.
+ * These could cause pointer alignment problems, so copy them to
+ * well aligned mbufs.
+ */
+ error = nfs_realign(&mrep, 2 * NFSX_UNSIGNED);
+ if (error == ENOMEM) {
+ m_freem(mrep);
+ AUTH_DESTROY(auth);
+ return (error);
+ }
+
+ md = mrep;
dpos = mtod(mrep, caddr_t);
tl = nfsm_dissect(u_int32_t *, NFSX_UNSIGNED);
if (*tl != 0) {
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