Messages in this thread |  | | Date | Sat, 27 Jan 2018 17:07:48 +0000 | From | Al Viro <> | Subject | Re: [RFC] apparent bogosity in unregister_ftrace_function_probe_func() |
| |
On Sat, Jan 27, 2018 at 01:59:56PM +0000, Dmitry Safonov wrote: > > > Incidentally, shouldn't filter_parse_regex("*[ab]", 5, &s, ¬) > > end up with s = "*[ab]"? We are returning MATCH_GLOB, after all, > > so we want the entire pattern there... I would've assumed that > > this is what the code in unregister_ftrace_function_probe_func() > > is trying to compensate for, the first oddity predates MATCH_GLOB... > > No, I don't think filter_parse_regex() should return the full regex.. > ftrace_match() expects search would be processed string, not a glob. > So, this unnecessary assignment broke unregistering multiple kprobs > with a middle/end pattern..
For substring - sure, but what about something like "*a*b" and "a*b"? AFAICS, filter_parse_regex() ends up with identical results in both cases - MATCH_GLOB and *search = "a*b". And no way for the caller to tell one from another.
IOW, it's a different bug sometimes obscured by the one in unregister_ftrace_function_probe_func(). filter_parse_regex() ought to revert to *search = buff; when it decides to return MATCH_GLOB. Or something like for (i = 0; i < len; i++) { if (buff[i] == '*') { if (!i) { type = MATCH_END_ONLY; } else if (i == len - 1) { if (type == MATCH_END_ONLY) type = MATCH_MIDDLE_ONLY; else type = MATCH_FRONT_ONLY; buff[i] = 0; break; } else { /* pattern continues, use full glob */ return MATCH_GLOB; } } else if (strchr("[?\\", buff[i])) { return MATCH_GLOB; } } if (buff[0] == '*') *search = buff + 1; for that matter - i.e. delay that "we want everything past the first character" until we are certain it's not a MATCH_GLOB.
That one was introduced by "ftrace: Support full glob matching" in 2016, AFAICS...
|  |