Messages in this thread | | | Date | Fri, 6 Jul 2018 09:13:23 +0200 | From | Oscar Salvador <> | Subject | Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library |
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On Thu, Jul 05, 2018 at 08:44:18AM -0700, Kees Cook wrote: > On Thu, Jul 5, 2018 at 7:55 AM, <osalvador@techadventures.net> wrote: > > From: Oscar Salvador <osalvador@suse.de> > > > > The current code does not make sure to page align bss before calling > > vm_brk(), and this can lead to a VM_BUG_ON() in __mm_populate() > > due to the requested lenght not being correctly aligned. > > > > Let us make sure to align it properly. > > > > Signed-off-by: Oscar Salvador <osalvador@suse.de> > > Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> > > Reported-by: syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com > > Wow. CONFIG_USELIB? I'm surprised distros are still using this. 32-bit > only, and libc5 and earlier only. > > Regardless, this appears to match the current bss alignment logic in > the main elf loader, so: > > Acked-by: Kees Cook <keescook@chromium.org> > > -Kees > > > --- > > fs/binfmt_elf.c | 5 ++--- > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > > index 0ac456b52bdd..816cc921cf36 100644 > > --- a/fs/binfmt_elf.c > > +++ b/fs/binfmt_elf.c > > @@ -1259,9 +1259,8 @@ static int load_elf_library(struct file *file) > > goto out_free_ph; > > } > > > > - len = ELF_PAGESTART(eppnt->p_filesz + eppnt->p_vaddr + > > - ELF_MIN_ALIGN - 1); > > - bss = eppnt->p_memsz + eppnt->p_vaddr; > > + len = ELF_PAGEALIGN(eppnt->p_filesz + eppnt->p_vaddr); > > + bss = ELF_PAGEALIGN(eppnt->p_memsz + eppnt->p_vaddr); > > if (bss > len) { > > error = vm_brk(len, bss - len); > > if (error) > > -- > > 2.13.6 > > CC Andrew
Hi Andrew,
in case this patch gets accepted, does it have to go through your tree? Or is it for someone else to take it?
Thanks -- Oscar Salvador SUSE L3
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