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Re: [tor-bugs] #19657 [Applications/Tor Browser]: ASan detects heap buffer overflow in Tor Browser 6.5a1 Hardened
#19657: ASan detects heap buffer overflow in Tor Browser 6.5a1 Hardened
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Reporter: cypherpunks | Owner: tbb-team
Type: defect | Status: new
Priority: High | Milestone:
Component: Applications/Tor Browser | Version:
Severity: Major | Resolution:
Keywords: tbb-crash | Actual Points:
Parent ID: | Points:
Reviewer: | Sponsor:
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Comment (by cypherpunks):
I've just seen #19417 (asm.js files are saved to disk and reloaded next
launch/on new identity). Looking at the backtraces I attached, it seems
Tor Browser is crashing whilst deserializing asm.js cache files.
My hunch is that this crash is actually caused by #19417. Two
observations:
1. I upgraded to 6.5a1 "in place" allowing the builtin updater to run.
This may have left asm.js cache files on disk.
2. Because we don't change the Firefox build-id between versions of Tor
Browser (as Georg noted in
https://trac.torproject.org/projects/tor/ticket/19417#comment:11 ) the
newly updated Tor Browser would try to load the old cache files, even
though they were created by a previous Firefox version.
Normally, Firefox would not load cache files from a previous version. If
the cache file format has changed at all between the two Tor Browser
versions then we could easily end up with a memory bug issue like this.
I'll try to confirm this hunch with some experiments now.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19657#comment:2>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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