Messages in this thread | | | Date | Fri, 24 Sep 2021 10:57:18 +0800 | Subject | Re: [PATCH] staging: vchip_arm: Fix misuse of %x | From | Guo Zhi <> |
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On 2021/9/23 13:19, Greg KH wrote: > On Thu, Sep 23, 2021 at 11:55:54AM +0800, Guo Zhi wrote: >> Pointers should be printed with %p or %px rather than >> cast to (unsigned long) and printed with %lx. >> Change %lx to %pK to print the pointers. >> >> Signed-off-by: Guo Zhi <qtxuning1999@sjtu.edu.cn> >> --- >> .../staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> index b5aac862a29..408e5fe710b 100644 >> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> @@ -591,11 +591,11 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, >> return VCHIQ_SUCCESS; >> >> vchiq_log_trace(vchiq_arm_log_level, >> - "%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx", >> - __func__, (unsigned long)user_service, >> + "%s - service %pK(%d,%p), reason %d, header %pK, instance %pK, bulk_userdata %pK", >> + __func__, user_service, >> service->localport, user_service->userdata, >> - reason, (unsigned long)header, >> - (unsigned long)instance, (unsigned long)bulk_userdata); >> + reason, header, >> + instance, bulk_userdata); > Why print this out at all? What uses this? Can it just be deleted? > > thanks, > > greg k-h
This information is printed for debugging usage.
But malicious user process can also print it through debugfs at /sys/kernel/debug.
As it can be used for debugging, it's a little radical to just delete.
Therefore, I suggest replacing %lx with %pK to avoid kernel address leakage.
thanks,
Guo
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