On Fri, 31 Jan 2014 16:06:06 -0700 Greg Pearson <greg.pear...@hp.com> wrote:
> Currently, update_note_header_size_elf64() and
> update_note_header_size_elf32() will add the size
> of a PT_NOTE entry to real_sz even if that causes real_sz
> to exceeds max_sz. This patch corrects the while loop logic
> in those routines to ensure that does not happen.
>
> One possible negative side effect of exceeding the max_sz
> limit is an allocation failure in merge_note_headers_elf64()
> or merge_note_headers_elf32() which would produce console
> output such as the following while booting the crash
> kernel.
>
> ...
>
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -468,12 +468,13 @@ static int __init update_note_header_size_elf64(const
> Elf64_Ehdr *ehdr_ptr)
> return rc;
> }
> nhdr_ptr = notes_section;
> - while (real_sz < max_sz) {
> - if (nhdr_ptr->n_namesz == 0)
> - break;
> + while (nhdr_ptr->n_namesz != 0) {
> sz = sizeof(Elf64_Nhdr) +
> ((nhdr_ptr->n_namesz + 3) & ~3) +
> ((nhdr_ptr->n_descsz + 3) & ~3);
> + /* Silently drop further PT_NOTE entries */
> + if ((real_sz + sz) > max_sz)
> + break;
What are the implications of silently dropping some notes? Should we
warn when it occurs?
> real_sz += sz;
> nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
> }
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