From: Sudeep Holla <sudeep.holla@xxxxxxx>
commit b71b55248a580e9c9befc4ae060539f1f8e477da upstream.
Currently ffa_drv->remove() is called unconditionally from
ffa_device_remove(). Since the driver registration doesn't check for it
and allows it to be registered without .remove callback, we need to check
for the presence of it before executing it from ffa_device_remove() to
above a NULL pointer dereference like the one below:
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
| Mem abort info:
| ESR = 0x0000000086000004
| EC = 0x21: IABT (current EL), IL = 32 bits
| SET = 0, FnV = 0
| EA = 0, S1PTW = 0
| FSC = 0x04: level 0 translation fault
| user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881cc8000
| [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
| Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP
| CPU: 3 PID: 130 Comm: rmmod Not tainted 6.3.0-rc7 #6
| Hardware name: FVP Base RevC (DT)
| pstate: 63402809 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=-c)
| pc : 0x0
| lr : ffa_device_remove+0x20/0x2c
| Call trace:
| 0x0
| device_release_driver_internal+0x16c/0x260
| driver_detach+0x90/0xd0
| bus_remove_driver+0xdc/0x11c
| driver_unregister+0x30/0x54
| ffa_driver_unregister+0x14/0x20
| cleanup_module+0x18/0xeec
| __arm64_sys_delete_module+0x234/0x378
| invoke_syscall+0x40/0x108
| el0_svc_common+0xb4/0xf0
| do_el0_svc+0x30/0xa4
| el0_svc+0x2c/0x7c
| el0t_64_sync_handler+0x84/0xf0
| el0t_64_sync+0x190/0x194
Fixes: 244f5d597e1e ("firmware: arm_ffa: Add missing remove callback to ffa_bus_type")
Link: https://lore.kernel.org/r/20230419-ffa_fixes_6-4-v2-1-d9108e43a176@xxxxxxx
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/arm_ffa/bus.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/firmware/arm_ffa/bus.c
+++ b/drivers/firmware/arm_ffa/bus.c
@@ -53,7 +53,8 @@ static void ffa_device_remove(struct dev
{
struct ffa_driver *ffa_drv = to_ffa_driver(dev->driver);
- ffa_drv->remove(to_ffa_dev(dev));
+ if (ffa_drv->remove)
+ ffa_drv->remove(to_ffa_dev(dev));
}
static int ffa_device_uevent(struct device *dev, struct kobj_uevent_env *env)
