6.6-stable review patch. If anyone has any objections, please let me know.
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From: Vladimir Oltean vladimir.oltean@nxp.com
[ Upstream commit c84f6ce918a9e6f4996597cbc62536bbf2247c96 ]
Russell King reports that a system with mv88e6xxx dereferences a NULL pointer when unbinding this driver: https://lore.kernel.org/netdev/Z_lRkMlTJ1KQ0kVX@shell.armlinux.org.uk/
The crash seems to be in devlink_region_destroy(), which is not NULL tolerant but is given a NULL devlink global region pointer.
At least on some chips, some devlink regions are conditionally registered since the blamed commit, see mv88e6xxx_setup_devlink_regions_global():
if (cond && !cond(chip)) continue;
These are MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. If the chip does not have an STU or PVT, it should crash like this.
To fix the issue, avoid unregistering those regions which are NULL, i.e. were skipped at mv88e6xxx_setup_devlink_regions_global() time.
Fixes: 836021a2d0e0 ("net: dsa: mv88e6xxx: Export cross-chip PVT as devlink region") Tested-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://patch.msgid.link/20250414212850.2953957-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/mv88e6xxx/devlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/dsa/mv88e6xxx/devlink.c b/drivers/net/dsa/mv88e6xxx/devlink.c index a08dab75e0c0c..f57fde02077d2 100644 --- a/drivers/net/dsa/mv88e6xxx/devlink.c +++ b/drivers/net/dsa/mv88e6xxx/devlink.c @@ -743,7 +743,8 @@ void mv88e6xxx_teardown_devlink_regions_global(struct dsa_switch *ds) int i;
for (i = 0; i < ARRAY_SIZE(mv88e6xxx_regions); i++) - dsa_devlink_region_destroy(chip->regions[i]); + if (chip->regions[i]) + dsa_devlink_region_destroy(chip->regions[i]); }
void mv88e6xxx_teardown_devlink_regions_port(struct dsa_switch *ds, int port)