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Improve UBSan documentation 

Add more checks, info on -fno-sanitize=..., and reference to 5/2021 UBSan Oracle blog.

Authored By: DianeMeirowitz
Reviewed By: hctim

Differential Revision: https://reviews.llvm.org/D106908
This commit is contained in:
Mitch Phillips 2021-08-02 14:56:31 -07:00
parent 6f6e9a867f
commit 65e9d7efb0
1 changed files with 7 additions and 1 deletions
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8
clang/docs/UndefinedBehaviorSanitizer.rst
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@ -12,7 +12,9 @@ UndefinedBehaviorSanitizer (UBSan) is a fast undefined behavior detector.
UBSan modifies the program at compile-time to catch various kinds of undefined UBSan modifies the program at compile-time to catch various kinds of undefined
behavior during program execution, for example: behavior during program execution, for example:
* Using misaligned or null pointer * Array subscript out of bounds, where the bounds can be statically determined
* Bitwise shifts that are out of bounds for their data type
* Dereferencing misaligned or null pointers
* Signed integer overflow * Signed integer overflow
* Conversion to, from, or between floating-point types which would * Conversion to, from, or between floating-point types which would
overflow the destination overflow the destination
@ -53,6 +55,7 @@ and define the desired behavior for each kind of check:
* ``-fsanitize=...``: print a verbose error report and continue execution (default); * ``-fsanitize=...``: print a verbose error report and continue execution (default);
* ``-fno-sanitize-recover=...``: print a verbose error report and exit the program; * ``-fno-sanitize-recover=...``: print a verbose error report and exit the program;
* ``-fsanitize-trap=...``: execute a trap instruction (doesn't require UBSan run-time support). * ``-fsanitize-trap=...``: execute a trap instruction (doesn't require UBSan run-time support).
* ``-fno-sanitize=...``: disable any check, e.g., -fno-sanitize=alignment.
Note that the ``trap`` / ``recover`` options do not enable the corresponding Note that the ``trap`` / ``recover`` options do not enable the corresponding
sanitizer, and in general need to be accompanied by a suitable ``-fsanitize=`` sanitizer, and in general need to be accompanied by a suitable ``-fsanitize=``
@ -357,6 +360,9 @@ For a file called ``/code/library/file.cpp``, here is what would be emitted:
More Information More Information
================ ================
* From Oracle blog, including a discussion of error messages:
`Improving Application Security with UndefinedBehaviorSanitizer (UBSan) and GCC
<https://blogs.oracle.com/linux/improving-application-security-with-undefinedbehaviorsanitizer-ubsan-and-gcc>`_
* From LLVM project blog: * From LLVM project blog:
`What Every C Programmer Should Know About Undefined Behavior `What Every C Programmer Should Know About Undefined Behavior
<http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html>`_ <http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html>`_