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Summary: llvm-objdump (via libObject) validates DYLD_INFO rebase and bind entries against the basic structure found in the Mach-O file before evaluating the contents of those entries. Certain malformed Mach-Os can defeat the validation check and force llvm-objdump (libObject) to crash. The previous logic verified a rebase or bind started in a valid Mach-O section, but did not verify that the section wholely contained the fixup. It also generally allows rebases or binds to start immediately after a valid section even if that range is not itself part of a valid section. Finally, bind and rebase opcodes that indicate more than one fixup (apply N times...) are not completely validated: only the first and final fixups are checked. The previous logic also rejected certain binaries as false positives. Some bind and rebase opcodes can modify the state machine such that the next bind or rebase will fail. libObject will reject these opcodes as invalid in order to be helpful and print an error message associated with the instruction that caused the problem, even though the binary is not actually illegal until it consumes the invalid state in the state machine. In other words, libObject may reject a Mach-O binary that Apple's dynamic linker may consider legal. The original version of macho-rebase-add-addr-uleb-too-big is an example of such a binary. I have replaced the existing checkSegAndOffset and checkCountAndSkip functions with a single function, checkSegAndOffsets, which validates all of the fixups realized by a DYLD_INFO opcode. checkSegAndOffsets verifies that a Mach-O section fully contains each fixup. Every fixup realized by an opcode is validated, and some (but not all!) inconsistencies in the state machine are allowed until a fixup is realized. This means that libObject may fail on an opcode that realizes a fixup, not on the opcode that introduced the arithmetic error. Existing test cases have been modified to reflect the changes in error messages returned by libObject. What's more, the test case for macho-rebase-add-addr-uleb-too-big has been modified so that it actually triggers the error condition; the new code in libObject considers the original test binary "legal". rdar://47797757 Reviewers: lhames, pete, ab Reviewed By: pete Subscribers: rupprecht, jdoerfert, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59574 llvm-svn: 356629 |
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| configure | ||
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| LICENSE.TXT | ||
| llvm.spec.in | ||
| LLVMBuild.txt | ||
| README.txt | ||
| RELEASE_TESTERS.TXT | ||
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