[ 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
