* [PATCH] fs, elf: Make sure to page align bss in load_elf_library @ 2018-07-05 14:55 osalvador 2018-07-05 15:44 ` Kees Cook 0 siblings, 1 reply; 5+ messages in thread From: osalvador @ 2018-07-05 14:55 UTC (permalink / raw) To: linux-fsdevel Cc: linux-mm, linux-kernel, mhocko, penguin-kernel, keescook, nicolas.pitre, Oscar Salvador 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 --- 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 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library 2018-07-05 14:55 [PATCH] fs, elf: Make sure to page align bss in load_elf_library osalvador @ 2018-07-05 15:44 ` Kees Cook 2018-07-06 7:13 ` Oscar Salvador 2018-07-06 22:55 ` Andrew Morton 0 siblings, 2 replies; 5+ messages in thread From: Kees Cook @ 2018-07-05 15:44 UTC (permalink / raw) To: osalvador Cc: linux-fsdevel, Linux-MM, LKML, Michal Hocko, Tetsuo Handa, Nicolas Pitre, Oscar Salvador 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 > -- Kees Cook Pixel Security ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library 2018-07-05 15:44 ` Kees Cook @ 2018-07-06 7:13 ` Oscar Salvador 2018-07-06 19:23 ` Kees Cook 2018-07-06 22:55 ` Andrew Morton 1 sibling, 1 reply; 5+ messages in thread From: Oscar Salvador @ 2018-07-06 7:13 UTC (permalink / raw) To: Kees Cook Cc: linux-fsdevel, Linux-MM, LKML, Michal Hocko, Tetsuo Handa, Nicolas Pitre, Oscar Salvador, Andrew Morton 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 ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library 2018-07-06 7:13 ` Oscar Salvador @ 2018-07-06 19:23 ` Kees Cook 0 siblings, 0 replies; 5+ messages in thread From: Kees Cook @ 2018-07-06 19:23 UTC (permalink / raw) To: Oscar Salvador Cc: linux-fsdevel, Linux-MM, LKML, Michal Hocko, Tetsuo Handa, Nicolas Pitre, Oscar Salvador, Andrew Morton On Fri, Jul 6, 2018 at 12:13 AM, Oscar Salvador <osalvador@techadventures.net> wrote: > 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? (FWIW, binfmt_elf changes have traditionally gone through -mm, yes.) -Kees -- Kees Cook Pixel Security ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library 2018-07-05 15:44 ` Kees Cook 2018-07-06 7:13 ` Oscar Salvador @ 2018-07-06 22:55 ` Andrew Morton 1 sibling, 0 replies; 5+ messages in thread From: Andrew Morton @ 2018-07-06 22:55 UTC (permalink / raw) To: Kees Cook Cc: osalvador, linux-fsdevel, Linux-MM, LKML, Michal Hocko, Tetsuo Handa, Nicolas Pitre, Oscar Salvador On Thu, 5 Jul 2018 08:44:18 -0700 Kees Cook <keescook@chromium.org> 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. Presumably doesn't happen much, but people who *are* enabling this will want the fix, so I added the cc:stable. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-07-06 22:55 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-07-05 14:55 [PATCH] fs, elf: Make sure to page align bss in load_elf_library osalvador 2018-07-05 15:44 ` Kees Cook 2018-07-06 7:13 ` Oscar Salvador 2018-07-06 19:23 ` Kees Cook 2018-07-06 22:55 ` Andrew Morton
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