From patchwork Mon Jan 13 14:24:31 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 309929 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 9F1872C00B7 for ; Tue, 14 Jan 2014 01:29:27 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1W2iW3-0005Fi-PC; Mon, 13 Jan 2014 14:29:23 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1W2iTO-0003pP-UW for kernel-team@lists.ubuntu.com; Mon, 13 Jan 2014 14:26:38 +0000 Received: from bl20-137-17.dsl.telepac.pt ([2.81.137.17] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1W2iTM-0001Rz-SA; Mon, 13 Jan 2014 14:26:37 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.5 68/96] mm: ensure get_unmapped_area() returns higher address than mmap_min_addr Date: Mon, 13 Jan 2014 14:24:31 +0000 Message-Id: <1389623099-18783-69-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1389623099-18783-1-git-send-email-luis.henriques@canonical.com> References: <1389623099-18783-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Cc: Linus Torvalds , Kiyoshi Owada , Andrew Morton , Akira Takeuchi X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.29 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Akira Takeuchi commit 2afc745f3e3079ab16c826be4860da2529054dd2 upstream. This patch fixes the problem that get_unmapped_area() can return illegal address and result in failing mmap(2) etc. In case that the address higher than PAGE_SIZE is set to /proc/sys/vm/mmap_min_addr, the address lower than mmap_min_addr can be returned by get_unmapped_area(), even if you do not pass any virtual address hint (i.e. the second argument). This is because the current get_unmapped_area() code does not take into account mmap_min_addr. This leads to two actual problems as follows: 1. mmap(2) can fail with EPERM on the process without CAP_SYS_RAWIO, although any illegal parameter is not passed. 2. The bottom-up search path after the top-down search might not work in arch_get_unmapped_area_topdown(). Note: The first and third chunk of my patch, which changes "len" check, are for more precise check using mmap_min_addr, and not for solving the above problem. [How to reproduce] --- test.c ------------------------------------------------- #include #include #include #include int main(int argc, char *argv[]) { void *ret = NULL, *last_map; size_t pagesize = sysconf(_SC_PAGESIZE); do { last_map = ret; ret = mmap(0, pagesize, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); // printf("ret=%p\n", ret); } while (ret != MAP_FAILED); if (errno != ENOMEM) { printf("ERR: unexpected errno: %d (last map=%p)\n", errno, last_map); } return 0; } --------------------------------------------------------------- $ gcc -m32 -o test test.c $ sudo sysctl -w vm.mmap_min_addr=65536 vm.mmap_min_addr = 65536 $ ./test (run as non-priviledge user) ERR: unexpected errno: 1 (last map=0x10000) Signed-off-by: Akira Takeuchi Signed-off-by: Kiyoshi Owada Reviewed-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings [bwh: Backported to 3.2: As we do not have vm_unmapped_area(), make arch_get_unmapped_area_topdown() calculate the lower limit for the new area's end address and then compare addresses with this instead of with len. In the process, fix an off-by-one error which could result in returning 0 if mm->mmap_base == len.] Signed-off-by: Akira Takeuchi [akira: Backported to 3.5: Based on Ben's backport for 3.2-stable kernel. ] Signed-off-by: Luis Henriques --- mm/mmap.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 7e24763..529f72c 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1443,7 +1443,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, struct vm_area_struct *vma; unsigned long start_addr; - if (len > TASK_SIZE) + if (len > TASK_SIZE - mmap_min_addr) return -ENOMEM; if (flags & MAP_FIXED) @@ -1452,7 +1452,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, if (addr) { addr = PAGE_ALIGN(addr); vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && (!vma || addr + len <= vma->vm_start)) return addr; } @@ -1515,9 +1515,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, struct vm_area_struct *vma; struct mm_struct *mm = current->mm; unsigned long addr = addr0, start_addr; + unsigned long low_limit = max(PAGE_SIZE, mmap_min_addr); /* requested length too big for entire address space */ - if (len > TASK_SIZE) + if (len > TASK_SIZE - mmap_min_addr) return -ENOMEM; if (flags & MAP_FIXED) @@ -1527,7 +1528,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, if (addr) { addr = PAGE_ALIGN(addr); vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && (!vma || addr + len <= vma->vm_start)) return addr; } @@ -1542,7 +1543,7 @@ try_again: /* either no address requested or can't fit in requested address hole */ start_addr = addr = mm->free_area_cache; - if (addr < len) + if (addr < low_limit + len) goto fail; addr -= len; @@ -1563,7 +1564,7 @@ try_again: /* try just below the current vma->vm_start */ addr = vma->vm_start-len; - } while (len < vma->vm_start); + } while (vma->vm_start >= low_limit + len); fail: /*