From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 110/118] fs/binfmt_elf.c: coredump: allow process with empty address space to coredump Date: Thu, 30 Jan 2020 22:17:10 -0800 Message-ID: <20200131061710.rGdjO2hok%akpm@linux-foundation.org> References: <20200130221021.5f0211c56346d5485af07923@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:38226 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725832AbgAaGRL (ORCPT ); Fri, 31 Jan 2020 01:17:11 -0500 In-Reply-To: <20200130221021.5f0211c56346d5485af07923@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: adobriyan@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: Alexey Dobriyan Subject: fs/binfmt_elf.c: coredump: allow process with empty address space to coredump Unmapping whole address space at once with munmap(0, (1ULL<<47) - 4096) or equivalent will create empty coredump. It is silly way to exit, however registers content may still be useful. The right to coredump is fundamental right of a process! Link: http://lkml.kernel.org/r/20191222150137.GA1277@avx2 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton --- fs/binfmt_elf.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/binfmt_elf.c~elf-coredump-allow-process-with-empty-address-space-to-coredump +++ a/fs/binfmt_elf.c @@ -1595,6 +1595,10 @@ static int fill_files_note(struct memelf if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */ return -EINVAL; size = round_up(size, PAGE_SIZE); + /* + * "size" can be 0 here legitimately. + * Let it ENOMEM and omit NT_FILE section which will be empty anyway. + */ data = kvmalloc(size, GFP_KERNEL); if (ZERO_OR_NULL_PTR(data)) return -ENOMEM; @@ -2257,9 +2261,13 @@ static int elf_core_dump(struct coredump dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE); + /* + * Zero vma process will get ZERO_SIZE_PTR here. + * Let coredump continue for register state at least. + */ vma_filesz = kvmalloc(array_size(sizeof(*vma_filesz), (segs - 1)), GFP_KERNEL); - if (ZERO_OR_NULL_PTR(vma_filesz)) + if (!vma_filesz) goto end_coredump; for (i = 0, vma = first_vma(current, gate_vma); vma != NULL; _