[syzbot] KASAN: vmalloc-out-of-bounds Write in ringbuf_map_alloc

syzbot
2022-02-01T05:40:22Z

Hello,

syzbot found the following issue on:

HEAD commit: 887a333c44eb Add linux-next specific files for 20220131
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=106ea200700000
kernel config: https://syzkaller.appspot.com/x/.config?x=a9a7db1ff785d5c0
dashboard link: https://syzkaller.appspot.com/bug?extid=5ad567a418794b9b5983
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in bpf_ringbuf_area_alloc kernel/bpf/ringbuf.c:110 [inline]
BUG: KASAN: vmalloc-out-of-bounds in bpf_ringbuf_alloc kernel/bpf/ringbuf.c:133 [inline]
BUG: KASAN: vmalloc-out-of-bounds in ringbuf_map_alloc kernel/bpf/ringbuf.c:172 [inline]
BUG: KASAN: vmalloc-out-of-bounds in ringbuf_map_alloc+0x725/0x7b0 kernel/bpf/ringbuf.c:148
Write of size 8 at addr ffffc9001653a078 by task syz-executor.2/9141

CPU: 0 PID: 9141 Comm: syz-executor.2 Not tainted 5.17.0-rc2-next-20220131-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xf/0x3e0 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
bpf_ringbuf_area_alloc kernel/bpf/ringbuf.c:110 [inline]
bpf_ringbuf_alloc kernel/bpf/ringbuf.c:133 [inline]
ringbuf_map_alloc kernel/bpf/ringbuf.c:172 [inline]
ringbuf_map_alloc+0x725/0x7b0 kernel/bpf/ringbuf.c:148
find_and_alloc_map kernel/bpf/syscall.c:128 [inline]
map_create kernel/bpf/syscall.c:863 [inline]
__sys_bpf+0xc0f/0x5f10 kernel/bpf/syscall.c:4622
__do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fab8b037059
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fab89fac168 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fab8b149f60 RCX: 00007fab8b037059
RDX: 0000000000000048 RSI: 0000000020000440 RDI: 0000000000000000
RBP: 00007fab8b09108d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff1a45415f R14: 00007fab89fac300 R15: 0000000000022000
</TASK>

Memory state around the buggy address:
ffffc90016539f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc90016539f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc9001653a000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
^
ffffc9001653a080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc9001653a100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

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