From 1fbede6e6f3dc6c1c33e84b6989cf8079d899f89 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Thu, 30 Jan 2020 22:17:10 -0800 Subject: [PATCH] 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 Signed-off-by: Linus Torvalds --- fs/binfmt_elf.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index abd10707826a..f4713ea76e82 100644 --- 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; -- 2.45.2