Patch "9p/xen: fix version parsing" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    9p/xen: fix version parsing

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     9p-xen-fix-version-parsing.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit b396367e8df2b5167d4e7452c80c4f65c0e28888
Author: Juergen Gross <jgross@xxxxxxxx>
Date:   Mon Jan 30 12:30:35 2023 +0100

    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@xxxxxxxx
    Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend")
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
    Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
    Signed-off-by: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index 6459c2356ff9f..c4aea1e3134c2 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -395,13 +395,19 @@ 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;
 	}