LU-10391 lnet: Fix NULL-deref in lnet_nidstr_r()

It is valid to pass NULL as the nid for lnet_nidstr_r() - it indicate
"any" nid.  LNET_NID_IS_ANY() tests for this and the function exits
early.

However, 'lnd' is assigned from "nid->nid_type" and 'nnum' from
"nid->nid_num", causing a NULL-pointer dereference.

So move these assignments later.

Fixes: 82a17076f880 ("LU-10391 lnet: introduce struct lnet_nid")
Test-Parameters: trivial
Test-Parameters: serverversion=2.12 serverdistro=el7.9 testlist=runtests
Test-Parameters: clientversion=2.12 testlist=runtests
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ie29dd4d0ef7fac0f11c1ece714278a7dd9860602
Reviewed-on: https://review.whamcloud.com/44838
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lnet/lnet/nidstrings.c b/lnet/lnet/nidstrings.c
index eb341d4..d732684 100644 (file)
--- a/lnet/lnet/nidstrings.c
+++ b/lnet/lnet/nidstrings.c
@@ -973,8 +973,8 @@ EXPORT_SYMBOL(libcfs_nid2str_r);
 char *
 libcfs_nidstr_r(const struct lnet_nid *nid, char *buf, size_t buf_size)
 {
-       __u32 nnum = be16_to_cpu(nid->nid_num);
-       __u32 lnd  = nid->nid_type;
+       __u32 nnum;
+       __u32 lnd;
        struct netstrfns *nf;
 
        if (LNET_NID_IS_ANY(nid)) {
@@ -983,6 +983,8 @@ libcfs_nidstr_r(const struct lnet_nid *nid, char *buf, size_t buf_size)
                return buf;
        }
 
+       nnum = be16_to_cpu(nid->nid_num);
+       lnd = nid->nid_type;
        nf = libcfs_lnd2netstrfns(lnd);
        if (nf) {
                size_t addr_len;