syzbot has found a reproducer for the following issue on: HEAD commit: cf6c9d12750c Add linux-next specific files for 20211022 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10bdd272b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=dd1cd3d631599df5 dashboard link: https://syzkaller.appspot.com/bug?extid=b904a1de3ec43711eba5 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12790a72b00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13eb76dcb00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b904a1de3ec43711eba5@xxxxxxxxxxxxxxxxxxxxxxxxx ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 6528 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Modules linked in: CPU: 1 PID: 6528 Comm: syz-executor149 Not tainted 5.15.0-rc6-next-20211022-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25 Code: 09 31 ff 89 de e8 27 1f 9f fd 84 db 0f 85 36 ff ff ff e8 3a 1b 9f fd 48 c7 c7 00 2e 04 8a c6 05 c7 25 a3 09 01 e8 92 ce 31 05 <0f> 0b e9 17 ff ff ff e8 1b 1b 9f fd 0f b6 1d ac 25 a3 09 31 ff 89 RSP: 0018:ffffc90001a4ff10 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88801d369d40 RSI: ffffffff815f06f8 RDI: fffff52000349fd4 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815ea4ce R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00005555565e9300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f842b6f56c0 CR3: 000000001bc33000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] __do_sys_memfd_secret mm/secretmem.c:221 [inline] __se_sys_memfd_secret mm/secretmem.c:194 [inline] __x64_sys_memfd_secret+0x182/0x1e0 mm/secretmem.c:194 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: 0033:0x7fbeb6a4cf89 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffde5076be8 EFLAGS: 00000246 ORIG_RAX: 00000000000001bf RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbeb6a4cf89 RDX: 00007fbeb6a0fe93 RSI: 0000000000000012 RDI: 0000000000080000 RBP: 00007fbeb6a10f70 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fbeb6a11000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK>
