From patchwork Wed May 9 20:02:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10390757 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B542760540 for ; Wed, 9 May 2018 20:02:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A82ED286FB for ; Wed, 9 May 2018 20:02:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 984A9286EE; Wed, 9 May 2018 20:02:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 061BF28703 for ; Wed, 9 May 2018 20:02:49 +0000 (UTC) Received: (qmail 24565 invoked by uid 550); 9 May 2018 20:02:47 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 24543 invoked from network); 9 May 2018 20:02:46 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=NrIBfyyqyx8jb8dbKBswbeGqrEMLMvOWV2ml3aS6UOY=; b=TdHN+xy/C3ZaS4Uj4jaeDn/pIxm/u+cvxhzJj/p0MrKQCXdxhg0ccayHRM3+hkgXe8 dyIB6iCdbyPnXG20jVmrUp15OiLfI6UXFKmm+mc2QC+kp1euHJlux4byKas3VVCHFMyx pRQff74b/dUAgJ+aERJJoPFb699PT4LK4xB/Y= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=NrIBfyyqyx8jb8dbKBswbeGqrEMLMvOWV2ml3aS6UOY=; b=kzNRNzm6dJsv92BFH6SpScWxZmVzcFU5S7MfGDlc0WVYcMyiDvfYakrGMqf/ofJpfm uBZ4NIYNjPpmzMh/rLDnf1GWtaZ0gPg2Z/Yhxb/cSY1ey3T6ao9ocsQFRisj3VrTnset 5CoGyPr64SVpiwfyCizeiNUYMBsLox4T8L+3soQMGsJkq3EQn3i9lNynjHlXHb6Oh0YF 9RyaBuISrC0wIoQN/u3GR8G/WaEjkRQz1loJIJwqnUZnFiwYHDSBn261eWT9sUJU3tr3 vIhVqeLcDnCu/Yb8nBHoCpiNach+MUcKKqKbrYlUVZC4dr+5L3PjWjdOJZ5x9doOU/Zo yKEQ== X-Gm-Message-State: ALQs6tBd7DctI/F7APTXj9wHXs7qtDjPOEcPKNoI42ETcrJoUhmoKkx6 isWE91FKUUevqMfVusDDIMsqqA== X-Google-Smtp-Source: AB8JxZpxxdaO3aUFb7uNIRCR0P036CSV0TW+q198g6+QJoFcrEXepADotHqHAH/uxJ4RdROUKS2f1Q== X-Received: by 2002:a65:6188:: with SMTP id c8-v6mr37001282pgv.131.1525896155022; Wed, 09 May 2018 13:02:35 -0700 (PDT) From: Kees Cook To: Matthew Wilcox Cc: Kees Cook , Rasmus Villemoes , Matthew Wilcox , LKML , Linux-MM , Kernel Hardening Subject: [PATCH v2 3/6] overflow.h: Add allocation size calculation helpers Date: Wed, 9 May 2018 13:02:20 -0700 Message-Id: <20180509200223.22451-4-keescook@chromium.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180509200223.22451-1-keescook@chromium.org> References: <20180509200223.22451-1-keescook@chromium.org> X-Virus-Scanned: ClamAV using ClamSMTP In preparation for replacing unchecked overflows for memory allocations, this creates helpers for the 3 most common calculations: array_size(a, b): 2-dimensional array array3_size(a, b, c): 3-dimensional array struct_size(ptr, member, n): struct followed by n-many trailing members Each of these return SIZE_MAX on overflow instead of wrapping around. (Additionally renames a variable named "array_size" to avoid future collision.) Co-developed-by: Matthew Wilcox Signed-off-by: Kees Cook --- drivers/md/dm-table.c | 10 +++--- include/linux/overflow.h | 73 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 0589a4da12bb..caa51dd351b6 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -548,14 +548,14 @@ static int adjoin(struct dm_table *table, struct dm_target *ti) * On the other hand, dm-switch needs to process bulk data using messages and * excessive use of GFP_NOIO could cause trouble. */ -static char **realloc_argv(unsigned *array_size, char **old_argv) +static char **realloc_argv(unsigned *size, char **old_argv) { char **argv; unsigned new_size; gfp_t gfp; - if (*array_size) { - new_size = *array_size * 2; + if (*size) { + new_size = *size * 2; gfp = GFP_KERNEL; } else { new_size = 8; @@ -563,8 +563,8 @@ static char **realloc_argv(unsigned *array_size, char **old_argv) } argv = kmalloc(new_size * sizeof(*argv), gfp); if (argv) { - memcpy(argv, old_argv, *array_size * sizeof(*argv)); - *array_size = new_size; + memcpy(argv, old_argv, *size * sizeof(*argv)); + *size = new_size; } kfree(old_argv); diff --git a/include/linux/overflow.h b/include/linux/overflow.h index c8890ec358a7..8712ff70995f 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -202,4 +202,77 @@ #endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */ +/** + * 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. + */ +static inline __must_check size_t array_size(size_t a, size_t b) +{ + size_t bytes; + + if (check_mul_overflow(a, b, &bytes)) + return SIZE_MAX; + + return bytes; +} + +/** + * 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. + */ +static inline __must_check size_t array3_size(size_t a, size_t b, size_t c) +{ + size_t bytes; + + if (check_mul_overflow(a, b, &bytes)) + return SIZE_MAX; + if (check_mul_overflow(bytes, c, &bytes)) + return SIZE_MAX; + + return bytes; +} + +static inline __must_check size_t __ab_c_size(size_t n, size_t size, size_t c) +{ + size_t bytes; + + if (check_mul_overflow(n, size, &bytes)) + return SIZE_MAX; + if (check_add_overflow(bytes, c, &bytes)) + return SIZE_MAX; + + return bytes; +} + +/** + * struct_size() - Calculate size of structure with trailing array. + * @p: Pointer to the structure. + * @member: Name of the array member. + * @n: Number of elements in the array. + * + * Calculates size of memory needed for structure @p followed by an + * array of @n @member elements. + * + * Return: number of bytes needed or SIZE_MAX on overflow. + */ +#define struct_size(p, member, n) \ + __ab_c_size(n, \ + sizeof(*(p)->member) + __must_be_array((p)->member),\ + sizeof(*(p))) + #endif /* __LINUX_OVERFLOW_H */