Messages in this thread | | | Subject | Re: WARNING: kmalloc bug in xdp_umem_create | From | Daniel Borkmann <> | Date | Tue, 12 Jun 2018 14:08:52 +0200 |
| |
On 06/10/2018 03:03 PM, Björn Töpel wrote: > Den sön 10 juni 2018 kl 14:53 skrev Tetsuo Handa > <penguin-kernel@i-love.sakura.ne.jp>: >> On 2018/06/10 20:52, Dmitry Vyukov wrote: >>> On Sun, Jun 10, 2018 at 11:31 AM, Björn Töpel <bjorn.topel@gmail.com> wrote: >>>> Den sön 10 juni 2018 kl 04:53 skrev Tetsuo Handa >>>> <penguin-kernel@i-love.sakura.ne.jp>: >>>>> On 2018/06/10 7:47, syzbot wrote: >>>>>> Hello, >>>>>> >>>>>> syzbot found the following crash on: >>>>>> >>>>>> HEAD commit: 7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k.. >>>>>> git tree: upstream >>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000 >>>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a >>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506 >>>>>> compiler: gcc (GCC) 8.0.1 20180413 (experimental) >>>>>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000 >>>>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000 >>>>>> >>>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>>>>> Reported-by: syzbot+4abadc5d69117b346506@syzkaller.appspotmail.com >>>>>> >>>>>> random: sshd: uninitialized urandom read (32 bytes read) >>>>>> random: sshd: uninitialized urandom read (32 bytes read) >>>>>> random: sshd: uninitialized urandom read (32 bytes read) >>>>>> random: sshd: uninitialized urandom read (32 bytes read) >>>>>> random: sshd: uninitialized urandom read (32 bytes read) >>>>>> WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996 >>>>>> Kernel panic - not syncing: panic_on_warn set ... >>>>> >>>>> syzbot gave up upon kmalloc(), but actually error handling path has >>>>> NULL pointer dereference bug. >>>> >>>> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit >>>> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages"). >>> >>> Let's tell syzbot about this: >>> >>> #syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages >>> >> Excuse me, but that patch fixes NULL pointer dereference which occurs after kmalloc()'s >> "WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996" >> message. That is, "Too large memory allocation" itself is not yet fixed. > > The code relies on that the sl{u,a,o}b layer says no, and the > setsockopt bails out. The warning could be opted out using > __GFP_NOWARN. Is there another preferred way? Two get_user_pages > calls, where the first call would set pages to NULL just to fault the > region? Walk the process' VMAs? Something else?
(Now resolved as well.)
#syz fix: xsk: silence warning on memory allocation failure
| |