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Kees Cook 1ab137a90e overflow: Implement size_t saturating arithmetic helpers
commit e1be43d9b5d0d1310dbd90185a8e5c7145dde40f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-09-04 13:14:51 +02:00
arch arm64: ACPI: NUMA: initialize all values of acpi_early_node_map to NUMA_NO_NODE 2024-09-04 13:14:49 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 12:51:38 +02:00
certs
crypto crypto: ecrdsa - Fix module auto-load on add_key 2024-06-16 13:28:51 +02:00
Documentation overflow: Implement size_t saturating arithmetic helpers 2024-09-04 13:14:51 +02:00
drivers drm/amdgpu: Actually check flags for all context ops. 2024-09-04 13:14:50 +02:00
fs fix bitmap corruption on close_range() with CLOSE_RANGE_UNSHARE 2024-09-04 13:14:50 +02:00
include overflow: Implement size_t saturating arithmetic helpers 2024-09-04 13:14:51 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:51:36 +02:00
ipc
kernel tracing: Fix overflow in get_free_elt() 2024-08-19 05:33:53 +02:00
lib overflow: Implement size_t saturating arithmetic helpers 2024-09-04 13:14:51 +02:00
LICENSES
mm memcg_write_event_control(): fix a user-triggerable oops 2024-09-04 13:14:50 +02:00
net netfilter: nf_tables: prefer nft_chain_validate 2024-08-19 05:33:54 +02:00
samples media: rename VFL_TYPE_GRABBER to _VIDEO 2024-03-26 18:22:22 -04:00
scripts kbuild: Fix '-S -c' in x86 stack protector scripts 2024-08-19 05:33:53 +02:00
security selinux: fix potential counting error in avc_add_xperms_decision() 2024-09-04 13:14:50 +02:00
sound ALSA: usb-audio: Support Yamaha P-125 quirk entry 2024-09-04 13:14:49 +02:00
tools bitmap: introduce generic optimized bitmap_size() 2024-09-04 13:14:50 +02:00
usr
virt KVM: async_pf: Cleanup kvm_setup_async_pf() 2024-05-02 16:18:32 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.282 2024-08-19 05:33:54 +02:00
README

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.