Messages in this thread | | | Date | Tue, 29 Mar 2005 18:59:52 -0500 | From | Ananth N Mavinakayanahalli <> | Subject | Re: kprobe_handler should check pre_handler function |
| |
On Tue, Mar 29, 2005 at 02:18:02PM -0500, William Cohen wrote: > Ananth N Mavinakayanahalli wrote: > >On Mon, Mar 28, 2005 at 04:10:32PM -0500, William Cohen wrote: > > > >Hi Will, > > > > > >>I found kprobes expects there to be a pre_handler function in the > >>structure. I was writing a probe that only needed a post_handler > >>function, no pre_handler function. The probe was tracking the > >>destinations of indirect calls and jumps, the probe needs to fire after > >>the instruction single steps to get the target address. The probe > >>crashed the machine because arch/i386/kernel/kprobe.c:kprobe_handler() > >>blindly calls p->pre_handler(). There should be a check to verify that > >>the pointer is non-null. There are cases where the pre_handler is not > >>needed and it would make sense to set it to NULL. Thus, a check should > >>be done for pre_handler like post_handler and fault_handler. > > > > > >You are right. The check for pre_handler is needed and here is a patch > >against 2.6.12-rc1-mm3 that does this. > > > >Thanks, > >Ananth > > Ananth, > > Thanks. It looks like it addresses the problem. Could you see about > getting this patch in the upstream kernel?
Will,
I think Andrew now has this in his patchset. It will probably be in the next -mm.
Thanks, Ananth - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |