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Facebook adds 5 divs, 9 spans and 30 CSS classes to every post in the timeline

(twitter.com)
550 points polskibus | 4 comments | 08 Feb 19 16:04 UTC | HN request time: 0s | source
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mholt ◴[08 Feb 19 18:22 UTC] No.19117116[source]▶
A few days ago [1], I found this filter for UBlock Origin to be working for me so far:

    facebook.com##[id^=hyperfeed_story_id_]:has([id*=feed_sub_title_]):has(span:has-text(/S.*p.*o.*n.*s.*o.*r.*e.*d/))
GitHub issue: https://github.com/uBlockOrigin/uAssets/issues/3367

[1]: https://twitter.com/mholt6/status/1092191140168622080

replies(1): >>19117313 #
1. testplzignore ◴[08 Feb 19 18:42 UTC] No.19117313[source]▶
If I worked at Facebook and was evil, I'd put some text in that span that caused catastrophic backtracking :)
replies(1): >>19117514 #
2. majewsky ◴[08 Feb 19 18:59 UTC] No.19117514[source]▶
Regexes can be evaluated in linear time, so you'd have to send gigabytes worth of text to cause any noticeable slowdown.
replies(1): >>19119787 #
3. MapleWalnut ◴[09 Feb 19 00:05 UTC] No.19119787[source]▶
I believe with lookahead/behind a regex is technically not "regular" anymore, so you can definitely DoS a regex without GB worth of text.
replies(1): >>19119973 #
4. saagarjha ◴[09 Feb 19 00:51 UTC] No.19119973{3}[source]▶
Sure, but that regex doesn't have lookahead/lookbehind?