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* hwasan: Improve precision of checks using short granule tags.Peter Collingbourne2019-07-091-12/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A short granule is a granule of size between 1 and `TG-1` bytes. The size of a short granule is stored at the location in shadow memory where the granule's tag is normally stored, while the granule's actual tag is stored in the last byte of the granule. This means that in order to verify that a pointer tag matches a memory tag, HWASAN must check for two possibilities: * the pointer tag is equal to the memory tag in shadow memory, or * the shadow memory tag is actually a short granule size, the value being loaded is in bounds of the granule and the pointer tag is equal to the last byte of the granule. Pointer tags between 1 to `TG-1` are possible and are as likely as any other tag. This means that these tags in memory have two interpretations: the full tag interpretation (where the pointer tag is between 1 and `TG-1` and the last byte of the granule is ordinary data) and the short tag interpretation (where the pointer tag is stored in the granule). When HWASAN detects an error near a memory tag between 1 and `TG-1`, it will show both the memory tag and the last byte of the granule. Currently, it is up to the user to disambiguate the two possibilities. Because this functionality obsoletes the right aligned heap feature of the HWASAN memory allocator (and because we can no longer easily test it), the feature is removed. Also update the documentation to cover both short granule tags and outlined checks. Differential Revision: https://reviews.llvm.org/D63908 llvm-svn: 365551
* [HWASAN] Updated HWASAN design document to better portray the chance of ↵Mitch Phillips2019-02-131-1/+2
| | | | | | | | | | | | | | missing a bug. Summary: Provided rule of thumb percentage chances of miss for 4 and 8 bit tag sizes. Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D58195 llvm-svn: 353990
* [Documentation] Use HTTPS whenever possibleEugene Zelenko2019-01-231-1/+1
| | | | | | Differential revision: https://reviews.llvm.org/D56946 llvm-svn: 351976
* [docs] Don't use the `asm` syntax highlighting (which our docs builderChandler Carruth2018-08-061-9/+9
| | | | | | | | | errors on) and clean up the formattting. This isn't actualy assembly anyways, so dropping the highlighting is probably for the best. llvm-svn: 338979
* [HWASan] Update HWASan assembly snippet in the docsAlex Shlyapnikov2018-04-241-9/+10
| | | | | | | | | | | | Summary: To complement https://reviews.llvm.org/D45840 Reviewers: eugenis Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D45996 llvm-svn: 330745
* [hwasan] update docsKostya Serebryany2018-03-141-14/+23
| | | | llvm-svn: 327471
* [hwasan] update the asm snippet in the docs to match the current default ↵Kostya Serebryany2018-02-281-2/+0
| | | | | | behaviour llvm-svn: 326373
* [hwasan] Add a paragraph on stack instrumentation.Evgeniy Stepanov2018-02-031-3/+10
| | | | | | | | | | Reviewers: kcc Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D42874 llvm-svn: 324163
* [hwasan] update the design docKostya Serebryany2017-12-181-9/+25
| | | | llvm-svn: 321027
* [hwasan] typo in docsKostya Serebryany2017-12-081-1/+1
| | | | llvm-svn: 320168
* update hwasan docsKostya Serebryany2017-12-071-8/+24
| | | | | | | | | | | | | | | | Summary: * use more readable name * document the hwasan attribute Reviewers: eugenis Reviewed By: eugenis Subscribers: llvm-commits, cfe-commits Differential Revision: https://reviews.llvm.org/D40938 llvm-svn: 320075
* design document for a hardware-assisted memory safety (HWAMS) tool, similar ↵Kostya Serebryany2017-12-041-0/+123
to AddressSanitizer Summary: preliminary design document for a hardware-assisted memory safety (HWAMS) tool, similar to AddressSanitizer The name TaggedAddressSanitizer and the rest of the document, are early draft, suggestions are welcome. The code will follow shortly. Reviewers: eugenis, alekseyshl Reviewed By: eugenis Subscribers: davidxl, cryptoad, fedor.sergeev, cfe-commits, llvm-commits Differential Revision: https://reviews.llvm.org/D40568 llvm-svn: 319684
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