devlink: fix xa_alloc_cyclic() error handling

JIRA: https://issues.redhat.com/browse/RHEL-75600

Upstream commit(s):
commit f3b97b7
Author: Michal Swiatkowski <[email protected]>
Date:   Wed Mar 12 10:52:49 2025 +0100

    devlink: fix xa_alloc_cyclic() error handling

    In case of returning 1 from xa_alloc_cyclic() (wrapping) ERR_PTR(1) will
    be returned, which will cause IS_ERR() to be false. Which can lead to
    dereference not allocated pointer (rel).

    Fix it by checking if err is lower than zero.

    This wasn't found in real usecase, only noticed. Credit to Pierre.

    Fixes: c137743 ("devlink: introduce object and nested devlink relationship infra")
    Signed-off-by: Michal Swiatkowski <[email protected]>
    Reviewed-by: Andrew Lunn <[email protected]>
    Reviewed-by: Jiri Pirko <[email protected]>
    Signed-off-by: David S. Miller <[email protected]>

Signed-off-by: Petr Oros <[email protected]>

Author: orosp

net/devlink/core.c

@@ -117,7 +117,7 @@ static struct devlink_rel *devlink_rel_alloc(void)
 
 	err = xa_alloc_cyclic(&devlink_rels, &rel->index, rel,
 			      xa_limit_32b, &next, GFP_KERNEL);
-	if (err) {
+	if (err < 0) {
 		kfree(rel);
 		return ERR_PTR(err);
 	}