Subject: Re: KASAN: vmalloc-out-of-bounds Read in bpf_trace_run7

From: syzbot <[email-masked]>
Date: Wed, 20 Jan 2021 15:09:24 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    7d68e382 bpf: Permit size-0 datasec
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1418c3c7500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e0c7843b8af99dff
dashboard link: https://syzkaller.appspot.com/bug?extid=fad5d91c7158ce568634
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1224daa4d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13dfabd0d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in __bpf_trace_run kernel/trace/bpf_trace.c:2088 [inline]
BUG: KASAN: vmalloc-out-of-bounds in bpf_trace_run7+0x411/0x420 kernel/trace/bpf_trace.c:2130
Read of size 8 at addr ffffc90000e5c030 by task syz-executor460/8508

CPU: 1 PID: 8508 Comm: syz-executor460 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5/0x2f8 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:396 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
 __bpf_trace_run kernel/trace/bpf_trace.c:2088 [inline]
 bpf_trace_run7+0x411/0x420 kernel/trace/bpf_trace.c:2130
 __bpf_trace_percpu_alloc_percpu+0x1dc/0x220 include/trace/events/percpu.h:10
 __traceiter_percpu_alloc_percpu+0x97/0xf0 include/trace/events/percpu.h:10
 trace_percpu_alloc_percpu include/trace/events/percpu.h:10 [inline]
 pcpu_alloc+0xba6/0x16f0 mm/percpu.c:1844
 bpf_prog_alloc+0x78/0x250 kernel/bpf/core.c:117
 bpf_prog_load+0x656/0x1f40 kernel/bpf/syscall.c:2152
 __do_sys_bpf+0x1251/0x4f00 kernel/bpf/syscall.c:4380
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x441659
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 8b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffebad746f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441659
RDX: 0000000000000078 RSI: 0000000020000200 RDI: 0000000000000005
RBP: 000000000001191b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402470
R13: 0000000000402500 R14: 0000000000000000 R15: 0000000000000000

Memory state around the buggy address:
 ffffc90000e5bf00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90000e5bf80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90000e5c000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                     ^
 ffffc90000e5c080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90000e5c100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================