Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753327AbbLVDlS (ORCPT ); Mon, 21 Dec 2015 22:41:18 -0500 Received: from mail-pa0-f49.google.com ([209.85.220.49]:34991 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753274AbbLVDlB (ORCPT ); Mon, 21 Dec 2015 22:41:01 -0500 From: Laura Abbott To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton Cc: Laura Abbott , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kees Cook , kernel-hardening@lists.openwall.com Subject: [RFC][PATCH 4/7] slob: Add support for sanitization Date: Mon, 21 Dec 2015 19:40:38 -0800 Message-Id: <1450755641-7856-5-git-send-email-laura@labbott.name> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1450755641-7856-1-git-send-email-laura@labbott.name> References: <1450755641-7856-1-git-send-email-laura@labbott.name> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2928 Lines: 97 The SLOB allocator does not clear objects on free. This is a security risk since sensitive data may exist long past its expected life span. Add support for clearing objects on free. All credit for the original work should be given to Brad Spengler and the PaX Team. Signed-off-by: Laura Abbott --- mm/slob.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/mm/slob.c b/mm/slob.c index 17e8f8c..37a4ecb 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -334,10 +334,21 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node) return b; } +static void slob_sanitize(struct kmem_cache *c, slob_t *b, int size) +{ +#ifdef CONFIG_SLAB_MEMORY_SANITIZE + if (c && (c->flags & SLAB_NO_SANITIZE)) + return; + + if (sanitize_slab) + memset(b, SLAB_MEMORY_SANITIZE_VALUE, size); +#endif +} + /* * slob_free: entry point into the slob allocator. */ -static void slob_free(void *block, int size) +static void slob_free(struct kmem_cache *c, void *block, int size) { struct page *sp; slob_t *prev, *next, *b = (slob_t *)block; @@ -365,6 +376,8 @@ static void slob_free(void *block, int size) return; } + slob_sanitize(c, block, size); + if (!slob_page_free(sp)) { /* This slob page is about to become partially free. Easy! */ sp->units = units; @@ -495,7 +508,7 @@ void kfree(const void *block) if (PageSlab(sp)) { int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); unsigned int *m = (unsigned int *)(block - align); - slob_free(m, *m + align); + slob_free(NULL, m, *m + align); } else __free_pages(sp, compound_order(sp)); } @@ -579,10 +592,10 @@ void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t gfp, int node) EXPORT_SYMBOL(kmem_cache_alloc_node); #endif -static void __kmem_cache_free(void *b, int size) +static void __kmem_cache_free(struct kmem_cache *c, void *b, int size) { if (size < PAGE_SIZE) - slob_free(b, size); + slob_free(c, b, size); else slob_free_pages(b, get_order(size)); } @@ -592,7 +605,7 @@ static void kmem_rcu_free(struct rcu_head *head) struct slob_rcu *slob_rcu = (struct slob_rcu *)head; void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu)); - __kmem_cache_free(b, slob_rcu->size); + __kmem_cache_free(NULL, b, slob_rcu->size); } void kmem_cache_free(struct kmem_cache *c, void *b) @@ -604,7 +617,7 @@ void kmem_cache_free(struct kmem_cache *c, void *b) slob_rcu->size = c->size; call_rcu(&slob_rcu->head, kmem_rcu_free); } else { - __kmem_cache_free(b, c->size); + __kmem_cache_free(NULL, b, c->size); } trace_kmem_cache_free(_RET_IP_, b); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/