Messages in this thread Patch in this message | | | Date | Sun, 22 Dec 2019 18:01:37 +0300 | From | Alexey Dobriyan <> | Subject | [PATCH -mm 3/3 v2] ELF, coredump: allow process with empty address space to coredump |
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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;
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