mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 20:02:17 +00:00
![Kees Cook](/assets/img/avatar_default.png)
While struct_size() is normally used in situations where the structure type already has a pointer instance, there are places where no variable is available. In the past, this has been worked around by using a typed NULL first argument, but this is a bit ugly. Add a helper to do this, and replace the handful of instances of the code pattern with it. Instances were found with this Coccinelle script: @struct_size_t@ identifier STRUCT, MEMBER; expression COUNT; @@ - struct_size((struct STRUCT *)\(0\|NULL\), + struct_size_t(struct STRUCT, MEMBER, COUNT) Suggested-by: Christoph Hellwig <hch@infradead.org> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com> Cc: Tony Nguyen <anthony.l.nguyen@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: James Smart <james.smart@broadcom.com> Cc: Keith Busch <kbusch@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: HighPoint Linux Team <linux@highpoint-tech.com> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumit Saxena <sumit.saxena@broadcom.com> Cc: Shivasharan S <shivasharan.srikanteshwara@broadcom.com> Cc: Don Brace <don.brace@microchip.com> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: Guo Xuenan <guoxuenan@huawei.com> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Daniel Latypov <dlatypov@google.com> Cc: kernel test robot <lkp@intel.com> Cc: intel-wired-lan@lists.osuosl.org Cc: netdev@vger.kernel.org Cc: linux-nvme@lists.infradead.org Cc: linux-scsi@vger.kernel.org Cc: megaraidlinux.pdl@broadcom.com Cc: storagedev@microchip.com Cc: linux-xfs@vger.kernel.org Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://lore.kernel.org/r/20230522211810.never.421-kees@kernel.org
312 lines
10 KiB
C
312 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0 OR MIT */
|
|
#ifndef __LINUX_OVERFLOW_H
|
|
#define __LINUX_OVERFLOW_H
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/limits.h>
|
|
#include <linux/const.h>
|
|
|
|
/*
|
|
* We need to compute the minimum and maximum values representable in a given
|
|
* type. These macros may also be useful elsewhere. It would seem more obvious
|
|
* to do something like:
|
|
*
|
|
* #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0)
|
|
* #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0)
|
|
*
|
|
* Unfortunately, the middle expressions, strictly speaking, have
|
|
* undefined behaviour, and at least some versions of gcc warn about
|
|
* the type_max expression (but not if -fsanitize=undefined is in
|
|
* effect; in that case, the warning is deferred to runtime...).
|
|
*
|
|
* The slightly excessive casting in type_min is to make sure the
|
|
* macros also produce sensible values for the exotic type _Bool. [The
|
|
* overflow checkers only almost work for _Bool, but that's
|
|
* a-feature-not-a-bug, since people shouldn't be doing arithmetic on
|
|
* _Bools. Besides, the gcc builtins don't allow _Bool* as third
|
|
* argument.]
|
|
*
|
|
* Idea stolen from
|
|
* https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html -
|
|
* credit to Christian Biere.
|
|
*/
|
|
#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
|
|
#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
|
|
#define type_min(T) ((T)((T)-type_max(T)-(T)1))
|
|
|
|
/*
|
|
* Avoids triggering -Wtype-limits compilation warning,
|
|
* while using unsigned data types to check a < 0.
|
|
*/
|
|
#define is_non_negative(a) ((a) > 0 || (a) == 0)
|
|
#define is_negative(a) (!(is_non_negative(a)))
|
|
|
|
/*
|
|
* Allows for effectively applying __must_check to a macro so we can have
|
|
* both the type-agnostic benefits of the macros while also being able to
|
|
* enforce that the return value is, in fact, checked.
|
|
*/
|
|
static inline bool __must_check __must_check_overflow(bool overflow)
|
|
{
|
|
return unlikely(overflow);
|
|
}
|
|
|
|
/**
|
|
* check_add_overflow() - Calculate addition with overflow checking
|
|
* @a: first addend
|
|
* @b: second addend
|
|
* @d: pointer to store sum
|
|
*
|
|
* Returns 0 on success.
|
|
*
|
|
* *@d holds the results of the attempted addition, but is not considered
|
|
* "safe for use" on a non-zero return value, which indicates that the
|
|
* sum has overflowed or been truncated.
|
|
*/
|
|
#define check_add_overflow(a, b, d) \
|
|
__must_check_overflow(__builtin_add_overflow(a, b, d))
|
|
|
|
/**
|
|
* check_sub_overflow() - Calculate subtraction with overflow checking
|
|
* @a: minuend; value to subtract from
|
|
* @b: subtrahend; value to subtract from @a
|
|
* @d: pointer to store difference
|
|
*
|
|
* Returns 0 on success.
|
|
*
|
|
* *@d holds the results of the attempted subtraction, but is not considered
|
|
* "safe for use" on a non-zero return value, which indicates that the
|
|
* difference has underflowed or been truncated.
|
|
*/
|
|
#define check_sub_overflow(a, b, d) \
|
|
__must_check_overflow(__builtin_sub_overflow(a, b, d))
|
|
|
|
/**
|
|
* check_mul_overflow() - Calculate multiplication with overflow checking
|
|
* @a: first factor
|
|
* @b: second factor
|
|
* @d: pointer to store product
|
|
*
|
|
* Returns 0 on success.
|
|
*
|
|
* *@d holds the results of the attempted multiplication, but is not
|
|
* considered "safe for use" on a non-zero return value, which indicates
|
|
* that the product has overflowed or been truncated.
|
|
*/
|
|
#define check_mul_overflow(a, b, d) \
|
|
__must_check_overflow(__builtin_mul_overflow(a, b, d))
|
|
|
|
/**
|
|
* check_shl_overflow() - Calculate a left-shifted value and check overflow
|
|
* @a: Value to be shifted
|
|
* @s: How many bits left to shift
|
|
* @d: Pointer to where to store the result
|
|
*
|
|
* Computes *@d = (@a << @s)
|
|
*
|
|
* Returns true if '*@d' cannot hold the result or when '@a << @s' doesn't
|
|
* make sense. Example conditions:
|
|
*
|
|
* - '@a << @s' causes bits to be lost when stored in *@d.
|
|
* - '@s' is garbage (e.g. negative) or so large that the result of
|
|
* '@a << @s' is guaranteed to be 0.
|
|
* - '@a' is negative.
|
|
* - '@a << @s' sets the sign bit, if any, in '*@d'.
|
|
*
|
|
* '*@d' will hold the results of the attempted shift, but is not
|
|
* considered "safe for use" if true is returned.
|
|
*/
|
|
#define check_shl_overflow(a, s, d) __must_check_overflow(({ \
|
|
typeof(a) _a = a; \
|
|
typeof(s) _s = s; \
|
|
typeof(d) _d = d; \
|
|
u64 _a_full = _a; \
|
|
unsigned int _to_shift = \
|
|
is_non_negative(_s) && _s < 8 * sizeof(*d) ? _s : 0; \
|
|
*_d = (_a_full << _to_shift); \
|
|
(_to_shift != _s || is_negative(*_d) || is_negative(_a) || \
|
|
(*_d >> _to_shift) != _a); \
|
|
}))
|
|
|
|
#define __overflows_type_constexpr(x, T) ( \
|
|
is_unsigned_type(typeof(x)) ? \
|
|
(x) > type_max(typeof(T)) : \
|
|
is_unsigned_type(typeof(T)) ? \
|
|
(x) < 0 || (x) > type_max(typeof(T)) : \
|
|
(x) < type_min(typeof(T)) || (x) > type_max(typeof(T)))
|
|
|
|
#define __overflows_type(x, T) ({ \
|
|
typeof(T) v = 0; \
|
|
check_add_overflow((x), v, &v); \
|
|
})
|
|
|
|
/**
|
|
* overflows_type - helper for checking the overflows between value, variables,
|
|
* or data type
|
|
*
|
|
* @n: source constant value or variable to be checked
|
|
* @T: destination variable or data type proposed to store @x
|
|
*
|
|
* Compares the @x expression for whether or not it can safely fit in
|
|
* the storage of the type in @T. @x and @T can have different types.
|
|
* If @x is a constant expression, this will also resolve to a constant
|
|
* expression.
|
|
*
|
|
* Returns: true if overflow can occur, false otherwise.
|
|
*/
|
|
#define overflows_type(n, T) \
|
|
__builtin_choose_expr(__is_constexpr(n), \
|
|
__overflows_type_constexpr(n, T), \
|
|
__overflows_type(n, T))
|
|
|
|
/**
|
|
* castable_to_type - like __same_type(), but also allows for casted literals
|
|
*
|
|
* @n: variable or constant value
|
|
* @T: variable or data type
|
|
*
|
|
* Unlike the __same_type() macro, this allows a constant value as the
|
|
* first argument. If this value would not overflow into an assignment
|
|
* of the second argument's type, it returns true. Otherwise, this falls
|
|
* back to __same_type().
|
|
*/
|
|
#define castable_to_type(n, T) \
|
|
__builtin_choose_expr(__is_constexpr(n), \
|
|
!__overflows_type_constexpr(n, T), \
|
|
__same_type(n, T))
|
|
|
|
/**
|
|
* size_mul() - Calculate size_t multiplication with saturation at SIZE_MAX
|
|
* @factor1: first factor
|
|
* @factor2: second factor
|
|
*
|
|
* Returns: calculate @factor1 * @factor2, both promoted to size_t,
|
|
* with any overflow causing the return value to be SIZE_MAX. The
|
|
* lvalue must be size_t to avoid implicit type conversion.
|
|
*/
|
|
static inline size_t __must_check size_mul(size_t factor1, size_t factor2)
|
|
{
|
|
size_t bytes;
|
|
|
|
if (check_mul_overflow(factor1, factor2, &bytes))
|
|
return SIZE_MAX;
|
|
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* size_add() - Calculate size_t addition with saturation at SIZE_MAX
|
|
* @addend1: first addend
|
|
* @addend2: second addend
|
|
*
|
|
* Returns: calculate @addend1 + @addend2, both promoted to size_t,
|
|
* with any overflow causing the return value to be SIZE_MAX. The
|
|
* lvalue must be size_t to avoid implicit type conversion.
|
|
*/
|
|
static inline size_t __must_check size_add(size_t addend1, size_t addend2)
|
|
{
|
|
size_t bytes;
|
|
|
|
if (check_add_overflow(addend1, addend2, &bytes))
|
|
return SIZE_MAX;
|
|
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* size_sub() - Calculate size_t subtraction with saturation at SIZE_MAX
|
|
* @minuend: value to subtract from
|
|
* @subtrahend: value to subtract from @minuend
|
|
*
|
|
* Returns: calculate @minuend - @subtrahend, both promoted to size_t,
|
|
* with any overflow causing the return value to be SIZE_MAX. For
|
|
* composition with the size_add() and size_mul() helpers, neither
|
|
* argument may be SIZE_MAX (or the result with be forced to SIZE_MAX).
|
|
* The lvalue must be size_t to avoid implicit type conversion.
|
|
*/
|
|
static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
|
|
{
|
|
size_t bytes;
|
|
|
|
if (minuend == SIZE_MAX || subtrahend == SIZE_MAX ||
|
|
check_sub_overflow(minuend, subtrahend, &bytes))
|
|
return SIZE_MAX;
|
|
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* array_size() - Calculate size of 2-dimensional array.
|
|
* @a: dimension one
|
|
* @b: dimension two
|
|
*
|
|
* Calculates size of 2-dimensional array: @a * @b.
|
|
*
|
|
* Returns: number of bytes needed to represent the array or SIZE_MAX on
|
|
* overflow.
|
|
*/
|
|
#define array_size(a, b) size_mul(a, b)
|
|
|
|
/**
|
|
* array3_size() - Calculate size of 3-dimensional array.
|
|
* @a: dimension one
|
|
* @b: dimension two
|
|
* @c: dimension three
|
|
*
|
|
* Calculates size of 3-dimensional array: @a * @b * @c.
|
|
*
|
|
* Returns: number of bytes needed to represent the array or SIZE_MAX on
|
|
* overflow.
|
|
*/
|
|
#define array3_size(a, b, c) size_mul(size_mul(a, b), c)
|
|
|
|
/**
|
|
* flex_array_size() - Calculate size of a flexible array member
|
|
* within an enclosing structure.
|
|
* @p: Pointer to the structure.
|
|
* @member: Name of the flexible array member.
|
|
* @count: Number of elements in the array.
|
|
*
|
|
* Calculates size of a flexible array of @count number of @member
|
|
* elements, at the end of structure @p.
|
|
*
|
|
* Return: number of bytes needed or SIZE_MAX on overflow.
|
|
*/
|
|
#define flex_array_size(p, member, count) \
|
|
__builtin_choose_expr(__is_constexpr(count), \
|
|
(count) * sizeof(*(p)->member) + __must_be_array((p)->member), \
|
|
size_mul(count, sizeof(*(p)->member) + __must_be_array((p)->member)))
|
|
|
|
/**
|
|
* struct_size() - Calculate size of structure with trailing flexible array.
|
|
* @p: Pointer to the structure.
|
|
* @member: Name of the array member.
|
|
* @count: Number of elements in the array.
|
|
*
|
|
* Calculates size of memory needed for structure of @p followed by an
|
|
* array of @count number of @member elements.
|
|
*
|
|
* Return: number of bytes needed or SIZE_MAX on overflow.
|
|
*/
|
|
#define struct_size(p, member, count) \
|
|
__builtin_choose_expr(__is_constexpr(count), \
|
|
sizeof(*(p)) + flex_array_size(p, member, count), \
|
|
size_add(sizeof(*(p)), flex_array_size(p, member, count)))
|
|
|
|
/**
|
|
* struct_size_t() - Calculate size of structure with trailing flexible array
|
|
* @type: structure type name.
|
|
* @member: Name of the array member.
|
|
* @count: Number of elements in the array.
|
|
*
|
|
* Calculates size of memory needed for structure @type followed by an
|
|
* array of @count number of @member elements. Prefer using struct_size()
|
|
* when possible instead, to keep calculations associated with a specific
|
|
* instance variable of type @type.
|
|
*
|
|
* Return: number of bytes needed or SIZE_MAX on overflow.
|
|
*/
|
|
#define struct_size_t(type, member, count) \
|
|
struct_size((type *)NULL, member, count)
|
|
|
|
#endif /* __LINUX_OVERFLOW_H */
|