netdev - [PATCH net v2 1/3] devlink: fix xa_alloc

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Message-ID: <20250312095251.2554708-2-michal.swiatkowski@linux.intel.com>
Date: Wed, 12 Mar 2025 10:52:49 +0100
From: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
To: netdev@...r.kernel.org
Cc: jiri@...nulli.us,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org,
	pierre@...ckhpc.com,
	hkallweit1@...il.com,
	linux@...linux.org.uk,
	maxime.chevallier@...tlin.com,
	christophe.leroy@...roup.eu,
	arkadiusz.kubalewski@...el.com,
	vadim.fedorenko@...ux.dev,
	Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
Subject: [PATCH net v2 1/3] 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: c137743bce02 ("devlink: introduce object and nested devlink relationship infra")
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
---
 net/devlink/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/devlink/core.c b/net/devlink/core.c
index f49cd83f1955..7203c39532fc 100644
--- a/net/devlink/core.c
+++ b/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);
 	}
-- 
2.42.0