syzbot


WARNING: suspicious RCU usage in __copy_msghdr_from_user

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 3066820034b5 rcu: Reject RCU_LOCKDEP_WARN() false positives
First crash: 619d, last: 619d

Sample crash report:
=============================
WARNING: suspicious RCU usage
5.13.0-rc3-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8304 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
no locks held by syz-executor.1/5309.

stack backtrace:
CPU: 1 PID: 5309 Comm: syz-executor.1 Not tainted 5.13.0-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+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x266/0x2c0 kernel/sched/core.c:8304
 __might_fault+0x6e/0x180 mm/memory.c:5067
 _copy_from_user+0x27/0x180 lib/usercopy.c:13
 copy_from_user include/linux/uaccess.h:192 [inline]
 __copy_msghdr_from_user+0x91/0x4b0 net/socket.c:2232
 copy_msghdr_from_user net/socket.c:2283 [inline]
 recvmsg_copy_msghdr net/socket.c:2535 [inline]
 ___sys_recvmsg+0xd5/0x200 net/socket.c:2607
 do_recvmmsg+0x24d/0x6d0 net/socket.c:2705
 __sys_recvmmsg net/socket.c:2784 [inline]
 __do_sys_recvmmsg net/socket.c:2807 [inline]
 __se_sys_recvmmsg net/socket.c:2800 [inline]
 __x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2800
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f63cecd6188 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665d9
RDX: 0000000000010106 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 000000000056c038
R13: 00007fff1aaa1baf R14: 00007f63cecd6300 R15: 0000000000022000

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci-upstream-kasan-gce-selinux-root 2021/05/28 04:03 upstream 97e5bf604b7a 858ea628 .config console log report info WARNING: suspicious RCU usage in __copy_msghdr_from_user
* Struck through repros no longer work on HEAD.