diff options
author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-05-02 00:31:45 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-17 13:02:20 +0300 |
commit | 6e48faad92be13166184d21506e4e54c79c13adc (patch) | |
tree | 740dd24b1fda880409946feb8dbca1a752062c9f /net/ipv4 | |
parent | f47d0d32fa94e815fdd78b8b88684873e67939f4 (diff) | |
download | linux-6e48faad92be13166184d21506e4e54c79c13adc.tar.xz |
tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().
[ Upstream commit f2db7230f73a80dbb179deab78f88a7947f0ab7e ]
Anderson Nascimento reported a use-after-free splat in tcp_twsk_unique()
with nice analysis.
Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation for
timewait hashdance"), inet_twsk_hashdance() sets TIME-WAIT socket's
sk_refcnt after putting it into ehash and releasing the bucket lock.
Thus, there is a small race window where other threads could try to
reuse the port during connect() and call sock_hold() in tcp_twsk_unique()
for the TIME-WAIT socket with zero refcnt.
If that happens, the refcnt taken by tcp_twsk_unique() is overwritten
and sock_put() will cause underflow, triggering a real use-after-free
somewhere else.
To avoid the use-after-free, we need to use refcount_inc_not_zero() in
tcp_twsk_unique() and give up on reusing the port if it returns false.
[0]:
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110
CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x86_64 #1
Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023
RIP: 0010:refcount_warn_saturate+0xe5/0x110
Code: 42 8e ff 0f 0b c3 cc cc cc cc 80 3d aa 13 ea 01 00 0f 85 5e ff ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8
RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027
RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0
RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0
R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84
R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0
FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0
PKRU: 55555554
Call Trace:
<TASK>
? refcount_warn_saturate+0xe5/0x110
? __warn+0x81/0x130
? refcount_warn_saturate+0xe5/0x110
? report_bug+0x171/0x1a0
? refcount_warn_saturate+0xe5/0x110
? handle_bug+0x3c/0x80
? exc_invalid_op+0x17/0x70
? asm_exc_invalid_op+0x1a/0x20
? refcount_warn_saturate+0xe5/0x110
tcp_twsk_unique+0x186/0x190
__inet_check_established+0x176/0x2d0
__inet_hash_connect+0x74/0x7d0
? __pfx___inet_check_established+0x10/0x10
tcp_v4_connect+0x278/0x530
__inet_stream_connect+0x10f/0x3d0
inet_stream_connect+0x3a/0x60
__sys_connect+0xa8/0xd0
__x64_sys_connect+0x18/0x20
do_syscall_64+0x83/0x170
entry_SYSCALL_64_after_hwframe+0x78/0x80
RIP: 0033:0x7f62c11a885d
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 8b 0d a3 45 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000020ccb004 RCX: 00007f62c11a885d
RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003
RBP: 00007f62c1091e90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0
R13: ffffffffffffff88 R14: 0000000000000000 R15: 00007ffe237885b0
</TASK>
Fixes: ec94c2696f0b ("tcp/dccp: avoid one atomic operation for timewait hashdance")
Reported-by: Anderson Nascimento <anderson@allelesecurity.com>
Closes: https://lore.kernel.org/netdev/37a477a6-d39e-486b-9577-3463f655a6b7@allelesecurity.com/
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240501213145.62261-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r-- | net/ipv4/tcp_ipv4.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index c7ffab37a34c..c464ced7137e 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -154,6 +154,12 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) if (tcptw->tw_ts_recent_stamp && (!twp || (reuse && time_after32(ktime_get_seconds(), tcptw->tw_ts_recent_stamp)))) { + /* inet_twsk_hashdance() sets sk_refcnt after putting twsk + * and releasing the bucket lock. + */ + if (unlikely(!refcount_inc_not_zero(&sktw->sk_refcnt))) + return 0; + /* In case of repair and re-using TIME-WAIT sockets we still * want to be sure that it is safe as above but honor the * sequence numbers and time stamps set as part of the repair @@ -174,7 +180,7 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) tp->rx_opt.ts_recent = tcptw->tw_ts_recent; tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; } - sock_hold(sktw); + return 1; } |