+ Peter Chen - Maintainer of CDNS3 driver
> >[ Resending with an address that should work for Felipe ] > >On Sat, 27 Feb 2021 14:18:02 -0500 >Steven Rostedt <rost...@goodmis.org> wrote: > >> On Fri, 26 Feb 2021 14:21:00 -0800 >> Linus Torvalds <torva...@linux-foundation.org> wrote: >> >> > On Fri, Feb 26, 2021 at 11:07 AM Steven Rostedt <rost...@goodmis.org> >> > wrote: >> > > >> > > The first patch scans the print fmts of the trace events looking for >> > > dereferencing pointers from %p*, and making sure that they refer back >> > > to the trace event itself. >> > > >> > > The second patch handles strings "%s" [..] >> > >> > Doing this at runtime really feels like the wrong thing to do. >> > >> > It won't even protect us from what happened - people like me and >> > Andrew won't even run those tracepoints in the first place, so we >> > won't notice. >> > >> > It really would be much better in every respect to have this done by >> > checkpatch, I think. >> >> And after fixing the parsing to not trigger false positives, an >> allyesconfig boot found this: >> >> event cdns3_gadget_giveback has unsafe dereference of argument 11 >> print_fmt: "%s: req: %p, req buff %p, length: %u/%u %s%s%s, status: %d, trb: >> [start:%d, end:%d: virt addr %pa], flags:%x SID: %u", >__get_str(name), REC->req, REC->buf, >> REC->actual, REC->length, REC->zero ? "Z" : "z", REC->short_not_ok ? "S" : >> "s", REC->no_interrupt ? "I" : "i", REC->status, REC- >>start_trb, REC->end_trb, REC->start_trb_addr, REC->flags, RE >> C->stream_id >> >> (as the above is from a trace event class, it triggered for every event >> in that class). >> >> As it looks like it uses %pa which IIUC from the printk code, it >> dereferences the pointer to find it's virtual address. The event has >> this as the field: >> >> __field(struct cdns3_trb *, start_trb_addr) >> >> Assigns it with: >> >> __entry->start_trb_addr = req->trb; >> >> And prints that with %pa, which will dereference pointer at the time of >> reading, where the address in question may no longer be around. That >> looks to me as a potential bug. >> >> [ Cc'd the people responsible for that code. ] >> >> -- Steve
