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authorLinus Torvalds <torvalds@linux-foundation.org>2022-03-22 05:46:41 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-22 05:46:41 +0300
commitd0858cbdef50d973ca6b38c0ed0cce54cb2b6182 (patch)
treed734e883782256d82381d6e5bdcea5f1abe0ba86 /Documentation/process
parent2142b7f0c6bbe1f9515ce3383de9f7a32a5a025b (diff)
parent02788ebcf521fe78c24eb221fd1ed7f86792c330 (diff)
downloadlinux-d0858cbdef50d973ca6b38c0ed0cce54cb2b6182.tar.xz
Merge tag 'overflow-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull overflow updates from Kees Cook: "These changes come in roughly two halves: support of Gustavo A. R. Silva's struct_size() work via additional helpers for catching overflow allocation size calculations, and conversions of selftests to KUnit (which includes some tweaks for UML + Clang): - Convert overflow selftest to KUnit - Convert stackinit selftest to KUnit - Implement size_t saturating arithmetic helpers - Allow struct_size() to be used in initializers" * tag 'overflow-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: lib: stackinit: Convert to KUnit um: Allow builds with Clang lib: overflow: Convert to Kunit overflow: Provide constant expression struct_size overflow: Implement size_t saturating arithmetic helpers test_overflow: Regularize test reporting output
Diffstat (limited to 'Documentation/process')
-rw-r--r--Documentation/process/deprecated.rst20
1 files changed, 17 insertions, 3 deletions
diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 388cb19f5dbb..a6e36d9c3d14 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -71,6 +71,9 @@ Instead, the 2-factor form of the allocator should be used::
foo = kmalloc_array(count, size, GFP_KERNEL);
+Specifically, kmalloc() can be replaced with kmalloc_array(), and
+kzalloc() can be replaced with kcalloc().
+
If no 2-factor form is available, the saturate-on-overflow helpers should
be used::
@@ -91,9 +94,20 @@ Instead, use the helper::
array usage and switch to a `flexible array member
<#zero-length-and-one-element-arrays>`_ instead.
-See array_size(), array3_size(), and struct_size(),
-for more details as well as the related check_add_overflow() and
-check_mul_overflow() family of functions.
+For other calculations, please compose the use of the size_mul(),
+size_add(), and size_sub() helpers. For example, in the case of::
+
+ foo = krealloc(current_size + chunk_size * (count - 3), GFP_KERNEL);
+
+Instead, use the helpers::
+
+ foo = krealloc(size_add(current_size,
+ size_mul(chunk_size,
+ size_sub(count, 3))), GFP_KERNEL);
+
+For more details, also see array3_size() and flex_array_size(),
+as well as the related check_mul_overflow(), check_add_overflow(),
+check_sub_overflow(), and check_shl_overflow() family of functions.
simple_strtol(), simple_strtoll(), simple_strtoul(), simple_strtoull()
----------------------------------------------------------------------