On 11/13/20 5:08 PM, Yonghong Song wrote: > > > On 11/12/20 9:37 PM, Matt Mullins wrote: >> On Wed, Nov 11, 2020 at 03:57:50PM +0100, Dmitry Vyukov wrote: >>> On Mon, Nov 2, 2020 at 12:54 PM syzbot >>> <syzbot+d29e58bb557324e55e5e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: >>>> >>>> Hello, >>>> >>>> syzbot found the following issue on: >>>> >>>> HEAD commit: 080b6f40 bpf: Don't rely on GCC __attribute__((optimize)) .. >>>> git tree: bpf >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1089d37c500000 >>>> kernel config: https://syzkaller.appspot.com/x/.config?x=58a4ca757d776bfe >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=d29e58bb557324e55e5e >>>> compiler: gcc (GCC) 10.1.0-syz 20200507 >>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10f4b032500000 >>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1371a47c500000 >>>> >>>> The issue was bisected to: >>>> >>>> commit 9df1c28bb75217b244257152ab7d788bb2a386d0 >>>> Author: Matt Mullins <mmullins@xxxxxx> >>>> Date: Fri Apr 26 18:49:47 2019 +0000 >>>> >>>> bpf: add writable context for raw tracepoints >>> >>> >>> We have a number of kernel memory corruptions related to bpf_trace_run now: >>> https://groups.google.com/g/syzkaller-bugs/search?q=kernel/trace/bpf_trace.c >>> >>> Can raw tracepoints "legally" corrupt kernel memory (a-la /dev/kmem)? >>> Or they shouldn't? >>> >>> Looking at the description of Matt's commit, it seems that corruptions >>> should not be possible (bounded buffer, checked size, etc). Then it >>> means it's a real kernel bug? >> >> This bug doesn't seem to be related to the writability of the >> tracepoint; it bisected to that commit simply because it used >> BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE for the reproducer and it EINVAL's >> before that program type was introduced. The BPF program it loads is >> pretty much a no-op. >> >> The problem here is a kmalloc failure injection into >> tracepoint_probe_unregister, but the error is ignored -- so the bpf >> program is freed even though the tracepoint is never unregistered. >> >> I have a first pass at a patch to pipe through the error code, but it's >> pretty ugly. It's also called from the file_operations ->release(), for > > Maybe you can still post the patch, so people can review and make suggestions which may lead to a *better* solution. ping This bug is still there. > >> which errors are solidly ignored in __fput(), so I'm not sure what the >> best way to handle ENOMEM is... >> >>> >>> >>> >>>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12b6c4da500000 >>>> final oops: https://syzkaller.appspot.com/x/report.txt?x=11b6c4da500000 >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=16b6c4da500000 >>>> >>>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>>> Reported-by: syzbot+d29e58bb557324e55e5e@xxxxxxxxxxxxxxxxxxxxxxxxx >>>> Fixes: 9df1c28bb752 ("bpf: add writable context for raw tracepoints") >>>> >>>> ================================================================== >>>> BUG: KASAN: vmalloc-out-of-bounds in __bpf_trace_run kernel/trace/bpf_trace.c:2045 [inline] >>>> BUG: KASAN: vmalloc-out-of-bounds in bpf_trace_run3+0x3e0/0x3f0 kernel/trace/bpf_trace.c:2083 >>>> Read of size 8 at addr ffffc90000e6c030 by task kworker/0:3/3754 >>>> >>>> CPU: 0 PID: 3754 Comm: kworker/0:3 Not tainted 5.9.0-syzkaller #0 >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >>>> Workqueue: 0x0 (events) >>>> Call Trace: >>>> __dump_stack lib/dump_stack.c:77 [inline] >>>> dump_stack+0x107/0x163 lib/dump_stack.c:118 >>>> print_address_description.constprop.0.cold+0x5/0x4c8 mm/kasan/report.c:385 >>>> __kasan_report mm/kasan/report.c:545 [inline] >>>> kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562 >>>> __bpf_trace_run kernel/trace/bpf_trace.c:2045 [inline] >>>> bpf_trace_run3+0x3e0/0x3f0 kernel/trace/bpf_trace.c:2083 >>>> __bpf_trace_sched_switch+0xdc/0x120 include/trace/events/sched.h:138 >>>> __traceiter_sched_switch+0x64/0xb0 include/trace/events/sched.h:138 >>>> trace_sched_switch include/trace/events/sched.h:138 [inline] >>>> __schedule+0xeb8/0x2130 kernel/sched/core.c:4520 >>>> schedule+0xcf/0x270 kernel/sched/core.c:4601 >>>> worker_thread+0x14c/0x1120 kernel/workqueue.c:2439 >>>> kthread+0x3af/0x4a0 kernel/kthread.c:292 >>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 >>>> >>>> >>>> Memory state around the buggy address: >>>> ffffc90000e6bf00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >>>> ffffc90000e6bf80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >>>>> ffffc90000e6c000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >>>> ^ >>>> ffffc90000e6c080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >>>> ffffc90000e6c100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >>>> ================================================================== > [...]
