[PLAT-6316] Fix SIGSEGV in bsg_ksmachgetThreadQueueName #1065
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nickdowell
changed the title
kattrali
approved these changes
Apr 9, 2021
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I don't entirely see how this would happen, at least based on the available xnu sources, where the addr is non-zero but also invalid, but a little extra safety is always welcome.
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The timing of this is wonderful. I just noticed we've seen 1500 instances of this crash in production and was about to open an issue 😅 |
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Goal
Fixes a crash that can occur in
bsg_ksmachgetThreadQueueNameChangeset
The
thread_identifier_info.dispatch_qaddrcan sometimes contain an invalid address, which will cause a crash if dereferenced. This is something that has been noted in the Crashlytics source code.bsg_ksmachcopyMem()is now used to read the contents of the memory without causing a crash if invalid.Testing
I was not able to reproduce the crash, but manual testing and the E2E tests confirm that the function continues to return the expected queue name.