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* overflow: Implement size_t saturating arithmetic helpersKees Cook2022-02-161-3/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to perform more open-coded replacements of common allocation size arithmetic, the kernel needs saturating (SIZE_MAX) helpers for multiplication, addition, and subtraction. For example, it is common in allocators, especially on realloc, to add to an existing size: p = krealloc(map->patch, sizeof(struct reg_sequence) * (map->patch_regs + num_regs), GFP_KERNEL); There is no existing saturating replacement for this calculation, and just leaving the addition open coded inside array_size() could potentially overflow as well. For example, an overflow in an expression for a size_t argument might wrap to zero: array_size(anything, something_at_size_max + 1) == 0 Introduce size_mul(), size_add(), and size_sub() helpers that implicitly promote arguments to size_t and saturated calculations for use in allocations. With these helpers it is also possible to redefine array_size(), array3_size(), flex_array_size(), and struct_size() in terms of the new helpers. As with the check_*_overflow() helpers, the new helpers use __must_check, though what is really desired is a way to make sure that assignment is only to a size_t lvalue. Without this, it's still possible to introduce overflow/underflow via type conversion (i.e. from size_t to int). Enforcing this will currently need to be left to static analysis or future use of -Wconversion. Additionally update the overflow unit tests to force runtime evaluation for the pathological cases. Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: Keith Busch <kbusch@kernel.org> Cc: Len Baker <len.baker@gmx.com> Signed-off-by: Kees Cook <keescook@chromium.org>
* docs: deprecated.rst: Clarify open-coded arithmetic with literalsLen Baker2021-10-261-2/+3
| | | | | | | | | | | | | | Although using literals for size calculation in allocator arguments may be harmless due to compiler warnings in case of overflows, it is better to refactor the code to avoid the use of open-coded arithmetic. So, clarify the preferred way in these cases. Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://lore.kernel.org/r/20210925143455.21221-1-len.baker@gmx.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* deprecated.rst: Include details on "no_hash_pointers"Kees Cook2021-07-251-1/+3
| | | | | | | | | Linus decided a debug toggle for %p was tolerable, so update the %p deprecation documentation. Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210723200526.3424128-1-keescook@chromium.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: deprecated.rst: Expand str*cpy() replacement notesKees Cook2020-10-211-18/+26
| | | | | | | | | | | The notes on replacing the deprecated str*cpy() functions didn't call enough attention to the change in return type. Add these details and clean up the language a bit more. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://lore.kernel.org/r/20201015231730.2138505-1-keescook@chromium.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: deprecated.rst: Update zero-length/one-element arrays sectionGustavo A. R. Silva2020-09-091-3/+3
| | | | | | | | | | | Update information in the zero-length and one-element arrays section and illustrate how to make use of the new flex_array_size() helper, together with struct_size() and a flexible-array member. Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200901010949.GA21398@embeddedor Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* deprecated.rst: Remove now removed uninitialized_varJoe Perches2020-08-311-18/+0
| | | | | | | | | It's now gone from the kernel so remove it from the deprecated API text. Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/r/5e10c1645dd8f735215cf54a74db0f8dd3f6cbd5.camel@perches.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: Fix function name trailing double-()sKees Cook2020-08-241-1/+1
| | | | | | | | | | I noticed a double-() in the deprecated.rst rendering today. Fix that one and two others in the Documentation/ tree. Acked-by: "Paul E. McKenney" <paulmck@kernel.org> # For RCU Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200817233207.4083538-1-keescook@chromium.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* Merge tag 'docs-5.9' of git://git.lwn.net/linuxLinus Torvalds2020-08-041-0/+118
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation updates from Jonathan Corbet: "It's been a busy cycle for documentation - hopefully the busiest for a while to come. Changes include: - Some new Chinese translations - Progress on the battle against double words words and non-HTTPS URLs - Some block-mq documentation - More RST conversions from Mauro. At this point, that task is essentially complete, so we shouldn't see this kind of churn again for a while. Unless we decide to switch to asciidoc or something...:) - Lots of typo fixes, warning fixes, and more" * tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits) scripts/kernel-doc: optionally treat warnings as errors docs: ia64: correct typo mailmap: add entry for <alobakin@marvell.com> doc/zh_CN: add cpu-load Chinese version Documentation/admin-guide: tainted-kernels: fix spelling mistake MAINTAINERS: adjust kprobes.rst entry to new location devices.txt: document rfkill allocation PCI: correct flag name docs: filesystems: vfs: correct flag name docs: filesystems: vfs: correct sync_mode flag names docs: path-lookup: markup fixes for emphasis docs: path-lookup: more markup fixes docs: path-lookup: fix HTML entity mojibake CREDITS: Replace HTTP links with HTTPS ones docs: process: Add an example for creating a fixes tag doc/zh_CN: add Chinese translation prefer section doc/zh_CN: add clearing-warn-once Chinese version doc/zh_CN: add admin-guide index doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label futex: MAINTAINERS: Re-add selftests directory ...
| * docs: deprecated.rst: Add zero-length and one-element arraysGustavo A. R. Silva2020-06-191-0/+118
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add zero-length and one-element arrays to the list. While I continue replacing zero-length and one-element arrays with flexible-array members, I need a reference to point people to, so they don't introduce more instances of such arrays. And while here, add a note to the "open-coded arithmetic in allocator arguments" section, on the use of struct_size() and the arrays-to-deprecate mentioned here. Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200608213711.GA22271@embeddedor Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | docs: deprecated.rst: Add uninitialized_var()Kees Cook2020-07-161-0/+18
|/ | | | | | | | | | | | Nothing should be using this macro, and the entire idea of tricking the compiler into silencing such warnings is a mistake. Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Joe Perches <joe@perches.com> Cc: linux-doc@vger.kernel.org Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
* docs: deprecated.rst: Add BUG()-familyKees Cook2020-03-201-0/+22
| | | | | | | | | | | | | | Linus continues to remind[1] people to stop using the BUG()-family of functions. We should have this better documented (even if checkpatch.pl has been warning[2] since 2015), so add more details to deprecated.rst, as a distinct place to point people to for guidance. [1] https://lore.kernel.org/lkml/CAHk-=whDHsbK3HTOpTF=ue_o04onRwTEaK_ZoJp_fjbqq4+=Jw@mail.gmail.com/ [2] https://git.kernel.org/linus/9d3e3c705eb395528fd8f17208c87581b134da48 Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/202003141524.59C619B51A@keescook Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: Remove :c:func: from process/deprecated.rstJonathan Corbet2020-03-101-15/+15
| | | | | | | Documentation/process/deprecated.rst has a lot of uses of :c:func:, which is, well, deprecated. Emacs query-replace-regexp to the rescue. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: deprecated.rst: Clean up fall-through detailsKees Cook2020-03-101-19/+29
| | | | | | | | | | | Add example of fall-through, list-ify the case ending statements, and adjust the markup for links and readability. While here, adjust strscpy() details to mention strscpy_pad(). Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Link: https://lore.kernel.org/r/202003041102.47A4E4B62@keescook Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: deprecated.rst: Add %p to the listKees Cook2020-03-101-0/+22
| | | | | | | | | Once in a while %p usage comes up, and I've needed to have a reference to point people to. Add %p details to deprecated.rst. Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/202003042301.F844A8C0EC@keescook Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* Documentation/process: Add fallthrough pseudo-keywordJoe Perches2019-10-111-10/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | Describe the fallthrough pseudo-keyword. Convert the coding-style.rst example to the keyword style. Add description and links to deprecated.rst. Miguel Ojeda comments on the eventual [[fallthrough]] syntax: "Note that C17/C18 does not have [[fallthrough]]. C++17 introduced it, as it is mentioned above. I would keep the __attribute__((fallthrough)) -> [[fallthrough]] change you did, though, since that is indeed the standard syntax (given the paragraph references C++17). I was told by Aaron Ballman (who is proposing them for C) that it is more or less likely that it becomes standardized in C2x. However, it is still not added to the draft (other attributes are already, though). See N2268 and N2269: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2268.pdf (fallthrough) http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2269.pdf (attributes in general)" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Makefile: Globally enable fall-through warningGustavo A. R. Silva2019-07-251-0/+14
| | | | | | | | | | | | | | | | Now that all the fall-through warnings have been addressed in the kernel, enable the fall-through warning globally. Also, update the deprecated.rst file to include implicit fall-through as 'deprecated' so people can be pointed to a single location for justification. Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Kees Cook <keescook@chromium.org> Cc: linux-kbuild@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
* doc:it_IT: translations for documents in process/Federico Vaga2019-03-181-0/+2
| | | | | | | | | | | | | | | | | Translated documents: - stable-kernel-rules.rst - deprecated.rst - kernel-enforcement-statement.rst - license-rules.rst Added document to have valid links - netdev-FAQ.rst Modifications to main documentation - add label in deprecated.rst Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* docs: Introduce deprecated APIs listKees Cook2018-10-181-0/+119
As discussed in the "API replacement/deprecation" thread[1], this makes an effort to document what things shouldn't get (re)added to the kernel, by introducing Documentation/process/deprecated.rst. [1] https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2018-September/005282.html Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>