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| author | Eric Dumazet <edumazet@google.com> | 2022-01-14 17:43:28 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-01-15 03:31:37 +0100 |
| commit | 9d6d7f1cb67cdee15f1a0e85aacfb924e0e02435 (patch) | |
| tree | 34a06c72834b8513c7830347dc5f71c29754fe14 /net/unix/scm.c | |
| parent | net: stmmac: Fix "Unbalanced pm_runtime_enable!" warning (diff) | |
| download | linux-9d6d7f1cb67cdee15f1a0e85aacfb924e0e02435.tar.xz linux-9d6d7f1cb67cdee15f1a0e85aacfb924e0e02435.zip | |
af_unix: annote lockless accesses to unix_tot_inflight & gc_in_progress
wait_for_unix_gc() reads unix_tot_inflight & gc_in_progress
without synchronization.
Adds READ_ONCE()/WRITE_ONCE() and their associated comments
to better document the intent.
BUG: KCSAN: data-race in unix_inflight / wait_for_unix_gc
write to 0xffffffff86e2b7c0 of 4 bytes by task 9380 on cpu 0:
unix_inflight+0x1e8/0x260 net/unix/scm.c:63
unix_attach_fds+0x10c/0x1e0 net/unix/scm.c:121
unix_scm_to_skb net/unix/af_unix.c:1674 [inline]
unix_dgram_sendmsg+0x679/0x16b0 net/unix/af_unix.c:1817
unix_seqpacket_sendmsg+0xcc/0x110 net/unix/af_unix.c:2258
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2409
___sys_sendmsg net/socket.c:2463 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
__do_sys_sendmmsg net/socket.c:2578 [inline]
__se_sys_sendmmsg net/socket.c:2575 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
read to 0xffffffff86e2b7c0 of 4 bytes by task 9375 on cpu 1:
wait_for_unix_gc+0x24/0x160 net/unix/garbage.c:196
unix_dgram_sendmsg+0x8e/0x16b0 net/unix/af_unix.c:1772
unix_seqpacket_sendmsg+0xcc/0x110 net/unix/af_unix.c:2258
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2409
___sys_sendmsg net/socket.c:2463 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
__do_sys_sendmmsg net/socket.c:2578 [inline]
__se_sys_sendmmsg net/socket.c:2575 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
value changed: 0x00000002 -> 0x00000004
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9375 Comm: syz-executor.1 Not tainted 5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: 9915672d4127 ("af_unix: limit unix_tot_inflight")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20220114164328.2038499-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/unix/scm.c')
| -rw-r--r-- | net/unix/scm.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/unix/scm.c b/net/unix/scm.c index 052ae709ce28..aa27a02478dc 100644 --- a/net/unix/scm.c +++ b/net/unix/scm.c @@ -60,7 +60,8 @@ void unix_inflight(struct user_struct *user, struct file *fp) } else { BUG_ON(list_empty(&u->link)); } - unix_tot_inflight++; + /* Paired with READ_ONCE() in wait_for_unix_gc() */ + WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1); } user->unix_inflight++; spin_unlock(&unix_gc_lock); @@ -80,7 +81,8 @@ void unix_notinflight(struct user_struct *user, struct file *fp) if (atomic_long_dec_and_test(&u->inflight)) list_del_init(&u->link); - unix_tot_inflight--; + /* Paired with READ_ONCE() in wait_for_unix_gc() */ + WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1); } user->unix_inflight--; spin_unlock(&unix_gc_lock); |