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Message-Id: <20220928081300.101516-3-gwan-gyeong.mun@intel.com> Date: Wed, 28 Sep 2022 11:12:53 +0300 From: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com> To: intel-gfx@...ts.freedesktop.org Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, mchehab@...nel.org, chris@...is-wilson.co.uk, matthew.auld@...el.com, thomas.hellstrom@...ux.intel.com, jani.nikula@...el.com, nirmoy.das@...el.com, airlied@...hat.com, daniel@...ll.ch, andi.shyti@...ux.intel.com, andrzej.hajda@...el.com, keescook@...omium.org, mauro.chehab@...ux.intel.com, linux@...musvillemoes.dk, vitor@...saru.org, dlatypov@...gle.com, ndesaulniers@...gle.com, trix@...hat.com, llvm@...ts.linux.dev, linux-hardening@...r.kernel.org, linux-sparse@...r.kernel.org, nathan@...nel.org, gustavoars@...nel.org, luc.vanoostenryck@...il.com Subject: [PATCH v13 2/9] overflow: Introduce check_assign() and check_assign_user_ptr() Add check_assign() macro which performs an assigning source value into destination pointer along with an overflow check and check_assign_user_ptr() macro which performs an assigning source value into destination pointer type variable along with an overflow check. If an explicit overflow check is required while assigning to a user-space ptr, assign_user_ptr() can be used instead of u64_to_user_ptr() to assign integers into __user pointers along with an overflow check. v3: Add is_type_unsigned() macro (Mauro) Modify overflows_type() macro to consider signed data types (Mauro) Fix the problem that safe_conversion() macro always returns true v4: Fix kernel-doc markups v6: Move macro addition location so that it can be used by other than drm subsystem (Jani, Mauro, Andi) Change is_type_unsigned to is_unsigned_type to have the same name form as is_signed_type macro v8: Add check_assign() and remove safe_conversion() (Kees) Fix overflows_type() to use gcc's built-in overflow function (Andrzej) Add overflows_ptr() to allow overflow checking when assigning a value into a pointer variable (G.G.) v9: Fix overflows_type() to use __builtin_add_overflow() instead of __builtin_add_overflow_p() (Andrzej) Fix overflows_ptr() to use overflows_type() with the unsigned long type (Andrzej) v10: Remove a redundant type checking for a pointer. (Andrzej) Use updated check_add_overflow macro instead of __builtin_add_overflow (G.G) Add check_assign_user_ptr() macro and drop overflows_ptr() macro(Kees) v11: Fix incorrect type assignment between different address spaces caused by the wrong use of __user macro. (kernel test robot) Update macro description (G.G) v12: Remove overflows_type() macro here. updated overflows_type() macro will be added in a subsequent patch (G.G) Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com> Cc: Thomas Hellström <thomas.hellstrom@...ux.intel.com> Cc: Matthew Auld <matthew.auld@...el.com> Cc: Nirmoy Das <nirmoy.das@...el.com> Cc: Jani Nikula <jani.nikula@...el.com> Cc: Andi Shyti <andi.shyti@...ux.intel.com> Cc: Andrzej Hajda <andrzej.hajda@...el.com> Cc: Mauro Carvalho Chehab <mauro.chehab@...ux.intel.com> Cc: Kees Cook <keescook@...omium.org> Reviewed-by: Mauro Carvalho Chehab <mchehab@...nel.org> (v5) Reviewed-by: Andrzej Hajda <andrzej.hajda@...el.com> (v9) Acked-by: Kees Cook <keescook@...omium.org> Reported-by: kernel test robot <lkp@...el.com> --- drivers/gpu/drm/i915/i915_user_extensions.c | 6 +-- include/linux/overflow.h | 44 +++++++++++++++++++++ 2 files changed, 47 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_user_extensions.c b/drivers/gpu/drm/i915/i915_user_extensions.c index c822d0aafd2d..80ec8390b0d8 100644 --- a/drivers/gpu/drm/i915/i915_user_extensions.c +++ b/drivers/gpu/drm/i915/i915_user_extensions.c @@ -50,11 +50,11 @@ int i915_user_extensions(struct i915_user_extension __user *ext, if (err) return err; - if (get_user(next, &ext->next_extension) || - overflows_type(next, ext)) + if (get_user(next, &ext->next_extension)) return -EFAULT; - ext = u64_to_user_ptr(next); + if (check_assign_user_ptr(next, ext)) + return -EFAULT; } return 0; diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 19dfdd74835e..8ccbfa46f0ed 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -5,6 +5,7 @@ #include <linux/compiler.h> #include <linux/limits.h> #include <linux/const.h> +#include <linux/types.h> /* * We need to compute the minimum and maximum values representable in a given @@ -127,6 +128,49 @@ static inline bool __must_check __must_check_overflow(bool overflow) (*_d >> _to_shift) != _a); \ })) +/** + * check_assign - perform an assigning source value into destination pointer + * along with an overflow check. + * + * @value: source value + * @ptr: Destination pointer address + * + * Returns: + * If the value would overflow the destination, it returns true. If not return + * false. When overflow does not occur, the assigning into destination from + * value succeeds. It follows the return policy as other check_*_overflow() + * functions return non-zero as a failure. + */ +#define check_assign(value, ptr) __must_check_overflow(({ \ + check_add_overflow(0, value, ptr); \ +})) + +/** + * check_assign_user_ptr - perform an assigning source value into destination + * pointer type variable along with an overflow check + * + * @value: source value; a source value is expected to have a value of a size + * that can be stored in a pointer-type variable. + * @ptr: destination pointer type variable + * + * u64_to_user_ptr can be used in the kernel to avoid warnings about integers + * and pointers of different sizes. But u64_to_user_ptr is not performing the + * checking of overflow. If you need an explicit overflow check while + * assigning, check_assign_user_ptr() can be used to assign integers into + * pointers along with an overflow check. If ptr is not a pointer type, + * a warning message outputs while compiling. + * + * Returns: + * If the value would overflow the destination, it returns true. If not return + * false. When overflow does not occur, the assigning into ptr from value + * succeeds. It follows the return policy as other check_*_overflow() functions + * return non-zero as a failure. + */ +#define check_assign_user_ptr(value, ptr) __must_check_overflow(({ \ + uintptr_t kptr; \ + check_assign(value, &kptr) ? 1 : (({ ptr = (void __user *)kptr; }), 0); \ +})) + /** * size_mul() - Calculate size_t multiplication with saturation at SIZE_MAX * -- 2.37.1
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