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authorJulian Lettner <jlettner@apple.com>2019-10-10 00:33:04 +0000
committerJulian Lettner <jlettner@apple.com>2019-10-10 00:33:04 +0000
commit51a6e79ff7df8a7a1ca79fdda4fe0aec571da26c (patch)
tree712268fabfbf0bbb7fbc6d9143e7295d7553268d /README.txt
parentbeb0403319a2b449c0db2cacdfef77061cdc6029 (diff)
downloadcompiler-rt-51a6e79ff7df8a7a1ca79fdda4fe0aec571da26c.tar.gz
[ASan] Do not misrepresent high value address dereferences as null dereferences
Dereferences with addresses above the 48-bit hardware addressable range produce "invalid instruction" (instead of "invalid access") hardware exceptions (there is no hardware address decoding logic for those bits), and the address provided by this exception is the address of the instruction (not the faulting address). The kernel maps the "invalid instruction" to SEGV, but fails to provide the real fault address. Because of this ASan lies and says that those cases are null dereferences. This downgrades the severity of a found bug in terms of security. In the ASan signal handler, we can not provide the real faulting address, but at least we can try not to lie. rdar://50366151 Reviewed By: vitalybuka Differential Revision: https://reviews.llvm.org/D68676 git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@374265 91177308-0d34-0410-b5e6-96231b3b80d8
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