From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 23/54] mm/mmap.c: add more sanity checks to get_unmapped_area() Date: Sun, 07 Jun 2020 21:41:18 -0700 Message-ID: <20200608044118.UTcHAF_ag%akpm@linux-foundation.org> References: <20200607212615.b050e41fac139a1e16fe00bd@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:37112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726929AbgFHElT (ORCPT ); Mon, 8 Jun 2020 00:41:19 -0400 In-Reply-To: <20200607212615.b050e41fac139a1e16fe00bd@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: agordeev@linux.ibm.com, akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: Alexander Gordeev Subject: mm/mmap.c: add more sanity checks to get_unmapped_area() Generic get_unmapped_area() function does sanity checks of address and length of the area to be mapped. Yet, it lacks checking against mmap_min_addr and mmap_end limits. At the same time the default implementation of functions arch_get_unmapped_area[_topdown]() and some architecture callbacks do mmap_min_addr and mmap_end checks on their own. Put additional checks into the generic code and do not let architecture callbacks to get away with a possible area outside of the allowed limits. That could also relieve arch_get_unmapped_area[_topdown]() callbacks of own address and length sanity checks. Link: http://lkml.kernel.org/r/d14f2cff3c891ef2c4b0337d737c6f04beacb124.1584958099.git.agordeev@linux.ibm.com Signed-off-by: Alexander Gordeev Signed-off-by: Andrew Morton --- mm/mmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/mmap.c~mm-mmapc-add-more-sanity-checks-to-get_unmapped_area +++ a/mm/mmap.c @@ -2193,12 +2193,13 @@ get_unmapped_area(struct file *file, uns unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); + const unsigned long mmap_end = arch_get_mmap_end(addr); unsigned long error = arch_mmap_check(addr, len, flags); if (error) return error; /* Careful about overflows.. */ - if (len > TASK_SIZE) + if (len > mmap_end - mmap_min_addr) return -ENOMEM; get_area = current->mm->get_unmapped_area; @@ -2219,7 +2220,7 @@ get_unmapped_area(struct file *file, uns if (IS_ERR_VALUE(addr)) return addr; - if (addr > TASK_SIZE - len) + if ((addr < mmap_min_addr) || (addr > mmap_end - len)) return -ENOMEM; if (offset_in_page(addr)) return -EINVAL; _