Messages in this thread | | | Date | Mon, 3 Feb 2014 16:38:13 -0500 | From | Vivek Goyal <> | Subject | Re: [PATCH v2] vmcore: prevent PT_NOTE p_memsz overflow during header update |
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On Mon, Feb 03, 2014 at 01:18:38PM -0700, Greg Pearson wrote:
[..] > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 2ca7ba0..051c803 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -468,12 +468,14 @@ 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); > + if ((real_sz + sz) > max_sz) { > + pr_warn("Warning: dropping PT_NOTE entry\n"); > + break; > + }
Hi Greg,
Couple of minor nits.
I think it is a good idea to give more data in warning which tells why are we dropping a note entry. May be something like.
"Warning: Total note entry size exceeded PT_NOTE memsz. Dropping PT_NOTE entry, n_namesz=<> n_descsz=<>".
Secondly, if there is only on note entry in a PT_NOTE header and we drop it, then that PT_NOTE header is empty and needs to be cleaned up.
I think you will have to modify get_note_number_and_size_elf64() and other relevant functions which are not expecting ->p_memsz=0.
Thanks Vivek
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