Messages in this thread Patch in this message | | | Date | Tue, 10 Apr 2018 21:03:53 +0300 | From | Alexey Dobriyan <> | Subject | [PATCH] coredump: fix spam with zero VMA process |
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Nobody ever tried to self destruct by unmapping whole address space at once:
munmap((void *)0, (1ULL << 47) - 4096);
Doing this produces 2 warnings for zero-length vmalloc allocations:
a.out[1353]: segfault at 7f80bcc4b757 ip 00007f80bcc4b757 sp 00007fff683939b8 error 14 a.out: vmalloc: allocation failure: 0 bytes, mode:0xcc0(GFP_KERNEL), nodemask=(null) ... a.out: vmalloc: allocation failure: 0 bytes, mode:0xcc0(GFP_KERNEL), nodemask=(null) ...
Fix is to switch to kvmalloc().
Steps to reproduce:
// vsyscall=none #include <sys/mman.h> #include <sys/resource.h> int main(void) { setrlimit(RLIMIT_CORE, &(struct rlimit){RLIM_INFINITY, RLIM_INFINITY}); munmap((void *)0, (1ULL << 47) - 4096); return 0; }
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> ---
fs/binfmt_elf.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
--- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1608,8 +1608,8 @@ static int fill_files_note(struct memelfnote *note) if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */ return -EINVAL; size = round_up(size, PAGE_SIZE); - data = vmalloc(size); - if (!data) + data = kvmalloc(size, GFP_KERNEL); + if (ZERO_OR_NULL_PTR(data)) return -ENOMEM; start_end_ofs = data + 2; @@ -1626,7 +1626,7 @@ static int fill_files_note(struct memelfnote *note) filename = file_path(file, name_curpos, remaining); if (IS_ERR(filename)) { if (PTR_ERR(filename) == -ENAMETOOLONG) { - vfree(data); + kvfree(data); size = size * 5 / 4; goto alloc; } @@ -1919,7 +1919,7 @@ static void free_note_info(struct elf_note_info *info) kfree(t); } kfree(info->psinfo.data); - vfree(info->files.data); + kvfree(info->files.data); } #else @@ -2135,7 +2135,7 @@ static void free_note_info(struct elf_note_info *info) /* Free data possibly allocated by fill_files_note(): */ if (info->notes_files) - vfree(info->notes_files->data); + kvfree(info->notes_files->data); kfree(info->prstatus); kfree(info->psinfo); @@ -2281,8 +2281,8 @@ static int elf_core_dump(struct coredump_params *cprm) if (segs - 1 > ULONG_MAX / sizeof(*vma_filesz)) goto end_coredump; - vma_filesz = vmalloc((segs - 1) * sizeof(*vma_filesz)); - if (!vma_filesz) + vma_filesz = kvmalloc((segs - 1) * sizeof(*vma_filesz), GFP_KERNEL); + if (ZERO_OR_NULL_PTR(vma_filesz)) goto end_coredump; for (i = 0, vma = first_vma(current, gate_vma); vma != NULL; @@ -2389,7 +2389,7 @@ static int elf_core_dump(struct coredump_params *cprm) cleanup: free_note_info(&info); kfree(shdr4extnum); - vfree(vma_filesz); + kvfree(vma_filesz); kfree(phdr4note); kfree(elf); out:
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