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Currently the kmalloc_obj conversion rules leave alone every allocation
sized to an integral type, or assigned to a pointer to one, so that byte
buffers keep being allocated with a byte count. That also leaves alone
arrays of multi-byte integers, such as
vals = kcalloc(n, sizeof(u32), GFP_KERNEL);
which count objects like any other array. At the same time the signed
types (s8 through s64 and their variants) were not in the list at all.
But these multi-byte types are better handled through the full
kmalloc_obj-style allocation, as they are, in fact, typed and aren't
just a byte string, so they would benefit from type checking.
Split INTEGRAL into BYTE_TYPES and MULTIBYTE_TYPES:
- Allocations sized by a byte type or a string literal, or assigned to
a pointer to a byte type, are still left alone.
- Allocations sized by a multi-byte type are converted when they are
assigned to a pointer, or a pointer to const, of that same type.
Other allocations sized by a multi-byte type are left alone, as their
target may be a pointer to an array.
- Allocations of other types assigned to a pointer to a multi-byte type
are still left alone.
- Arrays of pointers to integral types sized by type, such as
sizeof(char *), are still left alone, now including the signed
types, as their target may be a pointer to an array of pointers, like
"const char *(*fmts)[]". Sized as sizeof(*target), they are converted
like any other array.
List the signed types and the other spellings of the standard integer
types (short int, unsigned, long long int, and so on), so that a
declaration and a sizeof() that spell the same type differently still
match.
Assisted-by: LLM coccinelle
Link: https://patch.msgid.link/20260914223748.i.971-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
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