Messages in this thread | | | Date | Wed, 5 Feb 2014 08:43:55 -0500 | From | Vivek Goyal <> | Subject | Re: [PATCH v3] vmcore: prevent PT_NOTE p_memsz overflow during header update |
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On Wed, Feb 05, 2014 at 08:39:12AM -0500, Vivek Goyal wrote: > On Tue, Feb 04, 2014 at 04:25:52PM -0700, Greg Pearson wrote: > > [..] > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > > index 2ca7ba0..88d4585 100644 > > --- a/fs/proc/vmcore.c > > +++ b/fs/proc/vmcore.c > > @@ -468,17 +468,24 @@ 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: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n", > > + nhdr_ptr->n_namesz, nhdr_ptr->n_descsz); > > You will need line break in pr_warn(). Too long a line. Limit it 80 > columns per line. > > > + break; > > + } > > real_sz += sz; > > nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz); > > } > > kfree(notes_section); > > phdr_ptr->p_memsz = real_sz; > > + if (real_sz == 0) { > > + pr_warn("Warning: Zero PT_NOTE entries found\n"); > > + return -EINVAL; > > Given the fact that this is the first time I have heard about a PT_NOTE > being corrup, I will be fine with this patch too. If one encounters > an empty PT_NOTE, error out and don't create vmcore. > > So please repost this patch with line lenght fixed.
Hi Greg,
Is there any more debugging info on why a PT_NOTE is getting corrupt. Did you get a chance to debug it further. This patch is more of a band-aid and real problem is why note is getting corrupted and we need to chase that down and fix that.
Thanks Vivek
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