Major new iOS bug can crash iPhones and disable access to apps and iMessages
theverge.com
theverge.com
These repeated errors looks like classic system or normal accidents as defined by Perrow in his book.
I read it six times in rapid succession and it keeps flipping between being a supporting arguement for and against the parent comment.
We don't know what kind of and how many errors triggered the failure, nor do we know what the faults causing the errors were.
We certainly don't know what kind of hazard analysis they did and what kind of mitigations they have in place, nor do we know whether they accepted a specific amount of residual risk for e.g. economic or market pressure reasons.
We don't know what kind of QC they do.
Without this information, it's pointless to talk about how things feel or seem. This is a very large engineering organization, working on a very large and complex system. It's not possible to find the root cause (or any cause) of a failure by using guesswork or by reporting to familiar failure cases.
Au contraire! Without this information we can only talk about how things feel or seem.
I don't see how that's productive, what has been "produced" here? Even the reddit comment from an (alleged) Apple employee was contradicted by other (alleged) Apple employees.
Gathering any insights into Apple's quality issues does not seem to be possible at all from internet comments... that makes the whole thing misleading and pointless to me.
Incorrect. A low-privileged user can kill their own processes, which is the expected behavior of kill(-1). The only issue is the fact that this can apparently also kernel panic the machine. But the fact that it kills all the processes belonging to the user is the expected behavior of this call.
I do think a lot of these issues could be easily caught before shipment by having a well paid adversarial QA department, but at the same time it is easy to see why this is not done, despite all the griping on tech websites about code quality going down all across the board everywhere, it's not like people will stop buying iphones etc. so it's an easy ROI decision to continue with the "users are QA" mindset.
We've started on this path with Apps, we just need to lock it in with an open source OS that is simply a userdata securing app store.
Supposedly it's a normal Telugu character, but how could that have gotten past even minimal testing in Hyderabad? Or is it some strange combining corner case? Telugu script is kind of unusual in Unicode, since it is syllabic but has separate codepoints for vowels and consonants, so character rendering is done by combining a vowel and consonant character into a totally different character. (Apologies for probably oversimplifying and mangling that explanation.) This is unlike Japanese katakana and hiragana, which have separate Unicode code points for each syllable so rendering is straightforward.
U+0C1C U+0C4D U+0C1E U+200C U+0C3E
That looks like a non-trivial character. I wonder how many other crashing characters can be generated from this pattern.
JA is a consonant, VIRAMA indicates a lack of vowel, NYA is another consonant, and it's non-joined(?) with the vowel AA. Can a Telugu speaker explain what that's supposed to do?
It happens for Telugu, Devanagari, and Bengali, for pretty much any (C,C,V) choice in Telugu, for any (C,C,V) choice in Devanagari where the second consonant is 'ra', and any such choice in Telugu where the second consonant is 'ra' or 'ya'. Some vowels don't work.
<consonant, virama, consonant> usually forms a ligature in most indic scripts. usually, that ligature is formed by munging the first consonant and tacking it on to the second.
However, in Telugu, it works the other way around -- the first consonant stays the same, but the second consonant is munged and placed below it. As a result, many forms render <virama, consonant> as a sort of "composite combining character", with a placeholder for where the first consonant goes, and the second consonant below it.
In Devanagari, the 'ra' consonant also does this, and 'ra' and 'ya' in Telugu.
This also happens for all Kannada consonants, but I can't trigger the bug with Kannada.
ZWNJ isn't really specified for Devanagari or Telugu; it can both make the vowel render separately or do nothing. In Bengali for some vowels it changes their form; however this bug occurs for more than just those vowels.
More specifically, here's what the Unicode Consortium glossary defines for "Character":
> Character. (1) The smallest component of written language that has semantic value; refers to the abstract meaning and/or shape, rather than a specific shape (see also glyph), though in code tables some form of visual representation is essential for the reader’s understanding. (2) Synonym for abstract character. (3) The basic unit of encoding for the Unicode character encoding. (4) The English name for the ideographic written elements of Chinese origin. [See ideograph (2).]
$ sqlite3 ~/Library/Safari/History.db
SQLite version 3.19.3 2017-06-27 16:40:08
Enter ".help" for usage hints.
sqlite> delete from history_items where url = "https://pastebin.com/9Tr8ytTr";本気ですか？
Very nasty (reported upstream.)
Would be really nice if Apple would stop treating its beta software as a final release.
Looks like it rendered as two characters instead on one
Edit: it’s random (it show in the 3D Touch to preview) https://imgur.com/a/xb5XV
Now how to fix it...
* Have someone else send you a message
* Click the notification and it'll open their message
* Navigate back and delete the corrupting message
Option 2:
* Sign up for the ios beta program (free) https://beta.apple.com/sp/betaprogram/ and install the latest beta which isn't impacted.
This is why we shouldn't be writing new code in C.
function ThisWillNeverCrash() {
console.log('hello');
stack.push('it');
setTimeout(ThisWillNeverCrash, 0);
setTimeout(ThisWillNeverCrash, 0);
// my point in posting this was to demonstrate a bug ... that array will eventually run out of memory and this loops infinitely but not using a standard language loop construct... but I see someone didn’t think that was relevant
Now, if they're talking about memory safety bugs...
However the crash also occurs with a Bengali sequence, and ZWNJ does have an effect in Bengali, so that sequence is not "weird", if perhaps rare.
According to Wikipedia, the number of people speaking Telugu is 0.97% of the world. It's not even a statistical margin of error.
Still, how hard can it be to have a machine step through all of the possible combinations of every iOS-supported character set and jam them into iMessage to see if they're failsafe?
Depends on your priorities. I'd take occasional bugs over jitter, latency, CPU inefficiency, and excess memory usage. And all that in practical terms means C is very environmentally friendly.
>Mozilla made two previous attempts to parallelize its style system in C++, and both of them failed. But Rust’s fearless concurrency has made parallelism practical! https://blog.rust-lang.org/2017/11/14/Fearless-Concurrency-I...
[1] - https://github.com/kdeldycke/awesome-falsehood
[2] - https://www.joelonsoftware.com/2003/10/08/the-absolute-minim...
Also, non-C languages frequently implement lots of library features on top of C because it would be a ton of work not to (and slower), which means any language could be at risk.
But largely the issue is, when an error occurs, can the state change to [undefined]. In some languages, like C/C++, it is possible through bugs to enter an undefined state. In many higher level languages, all states are defined even if not all states are actually handled by the developer's code.
If all states are defined you can use tooling to look for states which aren't handled by any execution path, and ideally handle them. If they remain unhandled there is a documented way to handle the unhandled known state (e.g. global exception handlers).
In a language with undefined states that isn't possible, all you can do is look for areas likely to result in an undefined state, but even that is easier said than done.
Higher level languages save you from a few classes of bugs, and make it easier to find bugs because things are more narrowly defined.
There is absolutely no such thing as "all states are defined". This has nothing to do with the language. There is nothing magical about a "higher level language" to safeguard from failures. At best you could be referring to managed languages, where memory access and exceptions are controlled and the extent of a aborted execution is predetermined - but still not immune to just closing a process when they misbehave. That is precisely what a process should do. Nonetheless, nothing in this bug report indicates that the system is acting in an undefined manner. The library that failed may have, by design, been programmed to close when font rendering reached these conditions. We don't know if this was a signal abort or an intentional if (bad_outcome) close()
Any level from the most managed sandboxed level to the most host level process may fail, regardless of the language used.
I would think that they would attempt sending all possible characters, especially because they've had issues with this in the past.
I've used AFL [1] to generate semantically valid, crashing multi-statement SQL queries when given ~50 CPU days and a simplistic SQL-like database. All from thin air, with an empty text file as the initial testcase. It can also come up with valid JPEGs [2] given enough time.
[1] - http://lcamtuf.coredump.cx/afl/
[2] - https://lcamtuf.blogspot.ie/2014/11/pulling-jpegs-out-of-thi...
Likely the next two programs are disagreeing on character, and therefore widget size.
Yes. This seems like a somewhat embarrassing fail in terms of whatever automated testing Apple does. It's a pretty minimal and restricted case of fuzzing, in fact I'm not sure it'd qualify as "fuzzing" at all because here the crasher is just an actual Unicode character, part of a fixed set that can be completely run through in deterministic time. Unicode is certainly large in human terms but in terms of automated test data sets it's not.
Given the notorious difficulties and edge cases Unicode parsing has long created, testing every single individual character in Unicode as part of standard unit/regression testing seems like something that should just be done as a bare minimum for an operating system or parsing framework/library release. That's not to say there wouldn't be more complex inputs that would cause problems that sufficient fuzzing could discover, but this kind of a error from a single real language character shouldn't have slipped through, it's not random.
Unicode and image/document handling frameworks are both areas that should have extensive fuzzing as well as deterministic input sets for testing. They shouldn't need to be messed with much either once they're "done", so in the case of an org like Apple this is the sort of place where it might even make sense to really devote resources to getting at least some parts of it formally verified.
To be specific, here are the codepoints in the character from Pastebin:
U+0C1C [Lo] TELUGU LETTER JA
U+0C4D [Mn] TELUGU SIGN VIRAMA
U+0C1E [Lo] TELUGU LETTER NYA
U+200C [Cf] ZERO WIDTH NON-JOINER
U+0C3E [Mn] TELUGU VOWEL SIGN AA
To be honest, though, if someone on my team suggested we implement an automated test that tries sending every Unicode character (and it would be applied to every interface of every app and API, right?) I would have objected that this was an over-complicated, over-engineered solution that will probably be too slow.
I'd argue that a set of test data selected to cover a range of patterns, especially ones that are considered risky (either is know to have caused problems in the past or appear complicated or tricky) would have almost as good coverage and be an order of magnitude more useful.
The problem with "run-every-case" tests is that they start off slow and get exponentially slower if you try to go deep you very quickly end up with tests that take too long to run to be useful. (e.g., {every Unicode character} is one thing... {Every Unicode character} X {every interface and app} is a LOT more. {Every Unicode character} X {every interface and app} X {every build} X {every device model} X etc. is impossible). So you end up with very broad but very shallow tests. And that means less coverage ultimately, not more.
Generally, I think you'll get more efficient, effective, useful tests if you tailor the test data sets to the problems you see rather than going for blanket coverage.
Sure, but fuzzing and "throw everything and the kitchen sink at it" type testing will generally expose logic bugs you weren't aware existed. Aka the unknown unknowns. Its not like this is an either/or proposition, you could run the fuzzing type gauntlet tests every week or so.
But I agree it would be unreasonable to do that for every app that uses the library.
I don't think it's a no-brainer though.
And it is unreasonable to expect a testing technique to be applied in every case where it is reasonable to do so. There are a lot of techniques that are reasonable to use in any give case but it would be no sense at all to apply every one of them. To focus on this one, now, amounts to Monday morning quarterbacking. Once you know the bug it's easy to see how it could have been caught. Of course if you somehow knew of a bug ahead of time you wouldn't need any test at all!
IMO fast probabilistic total coverage test is better than no test or partial coverage.
https://openradar.appspot.com/radar?id=4987859723354112
Edit: Saw that link two days ago already, but just noticed that it's also mentioned in the article.
However, there are similar test cases for Bengali, and ZWNJ does have an effect on some Bengali vowels, so it's definitely a real world character in that case.
90% of android phones not having any recent updates - big deal. [0]
[0] https://www.sammobile.com/news/samsung-stops-galaxy-s8-andro...
And it's interesting that you bring Samsung that for 3 years issued patches every single month for my old Note 4. You may not get latest and greatest Android version immediately (missing the essential "hamburger emoji fix") but you'll still get security updates.
(Very bad joke on my part)
EDIT: apparently he did go into recovery but didn't lose his files.
He says you have to go in DFU, press shift and click on update then select the file for the 11.3 beta upgrade.