9p/xen: fix version parsing

[ Upstream commit f1956f4ec15195ec60976d9b5625326285ab102e ]

When connecting the Xen 9pfs frontend to the backend, the "versions"
Xenstore entry written by the backend is parsed in a wrong way.

The "versions" entry is defined to contain the versions supported by
the backend separated by commas (e.g. "1,2"). Today only version "1"
is defined. Unfortunately the frontend doesn't look for "1" being
listed in the entry, but it is expecting the entry to have the value
"1".

This will result in failure as soon as the backend will support e.g.
versions "1" and "2".

Fix that by scanning the entry correctly.

Link: https://lkml.kernel.org/r/20230130113036.7087-2-jgross@suse.com
Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index cf1b89ba522b4b3bab28bd6e2fa8202234a18816..80cc0289dd0d69db4550e8b1d034f4f299100da2 100644 (file)
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -377,13 +377,19 @@ static int xen_9pfs_front_probe(struct xenbus_device *dev,
        int ret, i;
        struct xenbus_transaction xbt;
        struct xen_9pfs_front_priv *priv = NULL;
-       char *versions;
+       char *versions, *v;
        unsigned int max_rings, max_ring_order, len = 0;
 
        versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
        if (IS_ERR(versions))
                return PTR_ERR(versions);
-       if (strcmp(versions, "1")) {
+       for (v = versions; *v; v++) {
+               if (simple_strtoul(v, &v, 10) == 1) {
+                       v = NULL;
+                       break;
+               }
+       }
+       if (v) {
                kfree(versions);
                return -EINVAL;
        }