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The end goal of the current buffer overflow detection work[0] is to gain full compile-time and run-time coverage of all detectable buffer overflows seen via array indexing or memcpy(), memmove(), and memset(). The str*() family of functions already have full coverage. While much of the work for these changes have been on-going for many releases (i.e. 0-element and 1-element array replacements, as well as avoiding false positives and fixing discovered overflows[1]), this series contains the foundational elements of several related buffer overflow detection improvements by providing new common helpers and FORTIFY_SOURCE changes needed to gain the introspection required for compiler visibility into array sizes. Also included are a handful of already Acked instances using the helpers (or related clean-ups), with many more waiting at the ready to be taken via subsystem-specific trees[2]. The new helpers are: - struct_group() for gaining struct member range introspection. - memset_after() and memset_startat() for clearing to the end of structures. - DECLARE_FLEX_ARRAY() for using flex arrays in unions or alone in structs. Also included is the beginning of the refactoring of FORTIFY_SOURCE to support memcpy() introspection, fix missing and regressed coverage under GCC, and to prepare to fix the currently broken Clang support. Finishing this work is part of the larger series[0], but depends on all the false positives and buffer overflow bug fixes to have landed already and those that depend on this series to land. As part of the FORTIFY_SOURCE refactoring, a set of both a compile-time and run-time tests are added for FORTIFY_SOURCE and the mem*()-family functions respectively. The compile time tests have found a legitimate (though corner-case) bug[6] already. Please note that the appearance of "panic" and "BUG" in the FORTIFY_SOURCE refactoring are the result of relocating existing code, and no new use of those code-paths are expected nor desired. Finally, there are two tree-wide conversions for 0-element arrays and flexible array unions to gain sane compiler introspection coverage that result in no known object code differences. After this series (and the changes that have now landed via netdev and usb), we are very close to finally being able to build with -Warray-bounds and -Wzero-length-bounds. However, due corner cases in GCC[3] and Clang[4], I have not included the last two patches that turn on these options, as I don't want to introduce any known warnings to the build. Hopefully these can be solved soon. [0] https://lore.kernel.org/lkml/20210818060533.3569517-1-keescook@chromium.org/ [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=FORTIFY_SOURCE [2] https://lore.kernel.org/lkml/202108220107.3E26FE6C9C@keescook/ [3] https://lore.kernel.org/lkml/3ab153ec-2798-da4c-f7b1-81b0ac8b0c5b@roeck-us.net/ [4] https://bugs.llvm.org/show_bug.cgi?id=51682 [5] https://lore.kernel.org/lkml/202109051257.29B29745C0@keescook/ [6] https://lore.kernel.org/lkml/20211020200039.170424-1-keescook@chromium.org/ -----BEGIN PGP SIGNATURE----- iQJKBAABCgA0FiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmGAFWcWHGtlZXNjb29r QGNocm9taXVtLm9yZwAKCRCJcvTf3G3AJmKFD/45MJdnvW5MhIEeW5tc5UjfcIPS ae+YvlEX/2ZwgSlTxocFVocE6hz7b6eCiX3dSAChPkPxsSfgeiuhjxsU+4ROnELR 04RqTA/rwT6JXfJcXbDPXfxDL4huUkgktAW3m1sT771AZspeap2GrSwFyttlTqKA +kTiZ3lXJVFcw10uyhfp3Lk6eFJxdf5iOjuEou5kBOQfpNKEOduRL2K15hSowOwB lARiAC+HbmN+E+npvDE7YqK4V7ZQ0/dtB0BlfqgTkn1spQz8N21kBAMpegV5vvIk A+qGHc7q2oyk4M14TRTidQHGQ4juW1Kkvq3NV6KzwQIVD+mIfz0ESn3d4tnp28Hk Y+OXTI1BRFlApQU9qGWv33gkNEozeyqMLDRLKhDYRSFPA9UKkpgXQRzeTzoLKyrQ 4B6n5NnUGcu7I6WWhpyZQcZLDsHGyy0vHzjQGs/NXtb1PzXJ5XIGuPdmx9pVMykk IVKnqRcWyGWahfh3asOnoXvdhi1No4NSHQ/ZHfUM+SrIGYjBMaUisw66qm3Fe8ZU lbO2CFkCsfGSoKNPHf0lUEGlkyxAiDolazOfflDNxdzzlZo2X1l/a7O/yoO4Pqul cdL0eDjiNoQ2YR2TSYPnXq5KSL1RI0tlfS8pH8k1hVhZsQx0wpAQ+qki0S+fLePV PdA9XB82G2tmqKc9cQ== =9xbT -----END PGP SIGNATURE----- Merge tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull overflow updates from Kees Cook: "The end goal of the current buffer overflow detection work[0] is to gain full compile-time and run-time coverage of all detectable buffer overflows seen via array indexing or memcpy(), memmove(), and memset(). The str*() family of functions already have full coverage. While much of the work for these changes have been on-going for many releases (i.e. 0-element and 1-element array replacements, as well as avoiding false positives and fixing discovered overflows[1]), this series contains the foundational elements of several related buffer overflow detection improvements by providing new common helpers and FORTIFY_SOURCE changes needed to gain the introspection required for compiler visibility into array sizes. Also included are a handful of already Acked instances using the helpers (or related clean-ups), with many more waiting at the ready to be taken via subsystem-specific trees[2]. The new helpers are: - struct_group() for gaining struct member range introspection - memset_after() and memset_startat() for clearing to the end of structures - DECLARE_FLEX_ARRAY() for using flex arrays in unions or alone in structs Also included is the beginning of the refactoring of FORTIFY_SOURCE to support memcpy() introspection, fix missing and regressed coverage under GCC, and to prepare to fix the currently broken Clang support. Finishing this work is part of the larger series[0], but depends on all the false positives and buffer overflow bug fixes to have landed already and those that depend on this series to land. As part of the FORTIFY_SOURCE refactoring, a set of both a compile-time and run-time tests are added for FORTIFY_SOURCE and the mem*()-family functions respectively. The compile time tests have found a legitimate (though corner-case) bug[6] already. Please note that the appearance of "panic" and "BUG" in the FORTIFY_SOURCE refactoring are the result of relocating existing code, and no new use of those code-paths are expected nor desired. Finally, there are two tree-wide conversions for 0-element arrays and flexible array unions to gain sane compiler introspection coverage that result in no known object code differences. After this series (and the changes that have now landed via netdev and usb), we are very close to finally being able to build with -Warray-bounds and -Wzero-length-bounds. However, due corner cases in GCC[3] and Clang[4], I have not included the last two patches that turn on these options, as I don't want to introduce any known warnings to the build. Hopefully these can be solved soon" Link: https://lore.kernel.org/lkml/20210818060533.3569517-1-keescook@chromium.org/ [0] Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=FORTIFY_SOURCE [1] Link: https://lore.kernel.org/lkml/202108220107.3E26FE6C9C@keescook/ [2] Link: https://lore.kernel.org/lkml/3ab153ec-2798-da4c-f7b1-81b0ac8b0c5b@roeck-us.net/ [3] Link: https://bugs.llvm.org/show_bug.cgi?id=51682 [4] Link: https://lore.kernel.org/lkml/202109051257.29B29745C0@keescook/ [5] Link: https://lore.kernel.org/lkml/20211020200039.170424-1-keescook@chromium.org/ [6] * tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (30 commits) fortify: strlen: Avoid shadowing previous locals compiler-gcc.h: Define __SANITIZE_ADDRESS__ under hwaddress sanitizer treewide: Replace 0-element memcpy() destinations with flexible arrays treewide: Replace open-coded flex arrays in unions stddef: Introduce DECLARE_FLEX_ARRAY() helper btrfs: Use memset_startat() to clear end of struct string.h: Introduce memset_startat() for wiping trailing members and padding xfrm: Use memset_after() to clear padding string.h: Introduce memset_after() for wiping trailing members/padding lib: Introduce CONFIG_MEMCPY_KUNIT_TEST fortify: Add compile-time FORTIFY_SOURCE tests fortify: Allow strlen() and strnlen() to pass compile-time known lengths fortify: Prepare to improve strnlen() and strlen() warnings fortify: Fix dropped strcpy() compile-time write overflow check fortify: Explicitly disable Clang support fortify: Move remaining fortify helpers into fortify-string.h lib/string: Move helper functions out of string.c compiler_types.h: Remove __compiletime_object_size() cm4000_cs: Use struct_group() to zero struct cm4000_dev region can: flexcan: Use struct_group() to zero struct flexcan_regs regions ... |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.