From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S969881AbdADXiQ (ORCPT ); Wed, 4 Jan 2017 18:38:16 -0500 Received: from mail.sigma-star.at ([95.130.255.111]:45996 "EHLO mail.sigma-star.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761951AbdADXh7 (ORCPT ); Wed, 4 Jan 2017 18:37:59 -0500 From: Richard Weinberger To: linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz, kirill.shutemov@linux.intel.com, jmarchan@redhat.com, gerald.schaefer@de.ibm.com, hannes@cmpxchg.org, luto@kernel.org, Richard Weinberger Subject: [PATCH] proc: Fix integer overflow of VmLib Date: Thu, 5 Jan 2017 00:29:18 +0100 Message-Id: <20170104232918.25598-1-richard@nod.at> X-Mailer: git-send-email 2.10.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org /proc//status can report extremely high VmLib values which will confuse monitoring tools. VmLib is mm->exec_vm minus text size, where exec_vm is the number of bytes backed by an executable memory mapping and text size is mm->end_code - mm->start_code as set up by binfmt. For the vast majority of all programs text size is smaller than exec_vm. But if a program interprets binaries on its own the calculation result can be negative. UserModeLinux is such an example. It installs and removes lots of PROT_EXEC mappings but mm->start_code and mm->start_code remain and VmLib turns negative. Fix this by detecting the overflow and just return 0. For interpreting the value reported by VmLib is anyway useless but returning 0 does at least not confuse userspace. Signed-off-by: Richard Weinberger --- fs/proc/task_mmu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8f96a49178d0..220091c29aa6 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -46,6 +46,8 @@ void task_mem(struct seq_file *m, struct mm_struct *mm) text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10; lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text; + if ((long)lib < 0) + lib = 0; swap = get_mm_counter(mm, MM_SWAPENTS); ptes = PTRS_PER_PTE * sizeof(pte_t) * atomic_long_read(&mm->nr_ptes); pmds = PTRS_PER_PMD * sizeof(pmd_t) * mm_nr_pmds(mm); -- 2.10.2