From: Simon Horman horms@kernel.org

stable inclusion from stable-v4.19.318 commit 47d28dde172696031c880c5778633cdca30394ee category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGSOT CVE: CVE-2024-42224

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 4c7f3950a9fd53a62b156c0fe7c3a2c43b0ba19b ]

Since commit a3c53be55c95 ("net: dsa: mv88e6xxx: Support multiple MDIO busses") mv88e6xxx_default_mdio_bus() has checked that the return value of list_first_entry() is non-NULL.

This appears to be intended to guard against the list chip->mdios being empty. However, it is not the correct check as the implementation of list_first_entry is not designed to return NULL for empty lists.

Instead, use list_first_entry_or_null() which does return NULL if the list is empty.

Flagged by Smatch. Compile tested only.

Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: Simon Horman horms@kernel.org Link: https://lore.kernel.org/r/20240430-mv88e6xx-list_empty-v3-1-c35c69d88d2e@ker... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Liu Jian liujian56@huawei.com --- drivers/net/dsa/mv88e6xxx/chip.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 43b00e8bcdcd..93c893731acb 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -231,8 +231,8 @@ struct mii_bus *mv88e6xxx_default_mdio_bus(struct mv88e6xxx_chip *chip) { struct mv88e6xxx_mdio_bus *mdio_bus;

- mdio_bus = list_first_entry(&chip->mdios, struct mv88e6xxx_mdio_bus, - list); + mdio_bus = list_first_entry_or_null(&chip->mdios, + struct mv88e6xxx_mdio_bus, list); if (!mdio_bus) return NULL;