From d67790ddf0219aa0ad3e13b53ae0a7619b3425a2 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 22 May 2023 14:18:13 -0700 Subject: overflow: Add struct_size_t() helper 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 Cc: Jesse Brandeburg Cc: Tony Nguyen Cc: "David S. Miller" Cc: Eric Dumazet Cc: Paolo Abeni Cc: James Smart Cc: Keith Busch Cc: Jens Axboe Cc: Sagi Grimberg Cc: HighPoint Linux Team Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: Kashyap Desai Cc: Sumit Saxena Cc: Shivasharan S Cc: Don Brace Cc: "Darrick J. Wong" Cc: Dave Chinner Cc: Guo Xuenan Cc: Gwan-gyeong Mun Cc: Nick Desaulniers Cc: Daniel Latypov Cc: kernel test robot 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 Acked-by: Martin K. Petersen Reviewed-by: Darrick J. Wong Reviewed-by: Gustavo A. R. Silva Reviewed-by: Christoph Hellwig Acked-by: Jakub Kicinski Reviewed-by: Alexander Lobakin Link: https://lore.kernel.org/r/20230522211810.never.421-kees@kernel.org --- include/linux/overflow.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'include/linux/overflow.h') diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 0e33b5cbdb9f..f9b60313eaea 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -283,7 +283,7 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) * @member: Name of the array member. * @count: Number of elements in the array. * - * Calculates size of memory needed for structure @p followed by an + * 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. @@ -293,4 +293,20 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend) 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 */ -- cgit v1.2.3