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Date:   Mon, 02 Nov 2020 03:54:19 -0800
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Subject: KASAN: vmalloc-out-of-bounds Read in bpf_trace_run3
From:   syzbot <syzbot+d29e58bb557324e55e5e@syzkaller.appspotmail.com>
To:     akpm@linux-foundation.org, andrii@kernel.org, ast@kernel.org,
        bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net,
        hawk@kernel.org, john.fastabend@gmail.com, kafai@fb.com,
        kpsingh@chromium.org, kuba@kernel.org,
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        rostedt@goodmis.org, songliubraving@fb.com,
        syzkaller-bugs@googlegroups.com, yhs@fb.com
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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@fb.com>
Date:   Fri Apr 26 18:49:47 2019 +0000

    bpf: add writable context for raw tracepoints

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@syzkaller.appspotmail.com
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
==================================================================


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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