Messages in this thread | | | Date | Mon, 27 Nov 2017 17:46:39 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 4/6] hw_breakpoint: Factor out __modify_user_hw_breakpoint function |
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On Mon, Nov 27, 2017 at 05:21:31PM +0100, Jiri Olsa wrote: > +static int __modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) > +{ > + u64 old_addr = bp->attr.bp_addr; > + u64 old_len = bp->attr.bp_len; > + int old_type = bp->attr.bp_type; > + bool modify = attr->bp_type != old_type; > + int err = 0; > + > + bp->attr.bp_addr = attr->bp_addr; > + bp->attr.bp_type = attr->bp_type; > + bp->attr.bp_len = attr->bp_len; > + > + err = validate_hw_breakpoint(bp); > + if (!err && modify) > + err = modify_bp_slot(bp, old_type); > + > + if (err) { > + bp->attr.bp_addr = old_addr; > + bp->attr.bp_type = old_type; > + bp->attr.bp_len = old_len; > + return err; > + } > + > + bp->attr.disabled = attr->disabled; > + return 0; > +}
I think this function is failing to check if anything else in the attr changes.
For example, someone could have added PERF_SAMPLE_BRANCH_STACK. That's something you'll fail to create breakpoints with, but this modification would 'accept'.
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