Messages in this thread Patch in this message | | | Date | Sun, 22 Dec 2019 17:44:21 +0300 | From | Alexey Dobriyan <> | Subject | [PATCH -mm 3/3] ELF, 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!
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> ---
fs/binfmt_elf.c | 10 +++++- tools/testing/selftests/exec/Makefile | 1 tools/testing/selftests/exec/coredump-zero-vma.c | 38 +++++++++++++++++++++++ 3 files changed, 48 insertions(+), 1 deletion(-)
--- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1595,6 +1595,10 @@ static int fill_files_note(struct memelfnote *note) 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_params *cprm) 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; --- a/tools/testing/selftests/exec/Makefile +++ b/tools/testing/selftests/exec/Makefile @@ -8,6 +8,7 @@ TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir # Makefile is a run-time dependency, since it's accessed by the execveat test TEST_FILES := Makefile +TEST_GEN_PROGS += coredump-zero-vma TEST_GEN_PROGS += recursion-depth EXTRA_CLEAN := $(OUTPUT)/subdir.moved $(OUTPUT)/execveat.moved $(OUTPUT)/xxxxx* new file mode 100644 --- /dev/null +++ b/tools/testing/selftests/exec/coredump-zero-vma.c @@ -0,0 +1,38 @@ +/* + * Copyright (c) 2019 Alexey Dobriyan + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +/* Test that unmapping whole address space at once doesn't do anything funny. */ +#include <stddef.h> +#include <sys/mman.h> +#include <sys/resource.h> + +#ifdef __x86_64__ +static const size_t len = ((size_t)1 << 47) - 4096; +#endif + +#ifdef __x86_64__ +int main(void) +{ + setrlimit(RLIMIT_CORE, &(struct rlimit){RLIM_INFINITY, RLIM_INFINITY}); + munmap(NULL, len); + /* And... it's gone! */ + return 1; +} +#else +int main(void) +{ + return 4; +} +#endif
| |