diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-10-24 11:43:31 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-10-28 13:53:40 -0700 |
| commit | a793183caa9afae907a0d7ddd2ffd57329369bf5 (patch) | |
| tree | ea8d3071c0999d6e0ede0e3fbb4da5da3aeacc3c | |
| parent | 7de4344f2abbaeda5c62211a8314dbd5da2bac6c (diff) | |
udp: fix data-race in udp_set_dev_scratch()
KCSAN reported a data-race in udp_set_dev_scratch() [1]
The issue here is that we must not write over skb fields
if skb is shared. A similar issue has been fixed in commit
89c22d8c3b27 ("net: Fix skb csum races when peeking")
While we are at it, use a helper only dealing with
udp_skb_scratch(skb)->csum_unnecessary, as this allows
udp_set_dev_scratch() to be called once and thus inlined.
[1]
BUG: KCSAN: data-race in udp_set_dev_scratch / udpv6_recvmsg
write to 0xffff888120278317 of 1 bytes by task 10411 on cpu 1:
udp_set_dev_scratch+0xea/0x200 net/ipv4/udp.c:1308
__first_packet_length+0x147/0x420 net/ipv4/udp.c:1556
first_packet_length+0x68/0x2a0 net/ipv4/udp.c:1579
udp_poll+0xea/0x110 net/ipv4/udp.c:2720
sock_poll+0xed/0x250 net/socket.c:1256
vfs_poll include/linux/poll.h:90 [inline]
do_select+0x7d0/0x1020 fs/select.c:534
core_sys_select+0x381/0x550 fs/select.c:677
do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
__do_sys_pselect6 fs/select.c:784 [inline]
__se_sys_pselect6 fs/select.c:769 [inline]
__x64_sys_pselect6+0x12e/0x170 fs/select.c:769
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffff888120278317 of 1 bytes by task 10413 on cpu 0:
udp_skb_csum_unnecessary include/net/udp.h:358 [inline]
udpv6_recvmsg+0x43e/0xe90 net/ipv6/udp.c:310
inet6_recvmsg+0xbb/0x240 net/ipv6/af_inet6.c:592
sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871
___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480
do_recvmmsg+0x19a/0x5c0 net/socket.c:2601
__sys_recvmmsg+0x1ef/0x200 net/socket.c:2680
__do_sys_recvmmsg net/socket.c:2703 [inline]
__se_sys_recvmmsg net/socket.c:2696 [inline]
__x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10413 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/udp.c | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 345a3d43f5a6..d1ed160af202 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1316,6 +1316,20 @@ static void udp_set_dev_scratch(struct sk_buff *skb) scratch->_tsize_state |= UDP_SKB_IS_STATELESS; } +static void udp_skb_csum_unnecessary_set(struct sk_buff *skb) +{ + /* We come here after udp_lib_checksum_complete() returned 0. + * This means that __skb_checksum_complete() might have + * set skb->csum_valid to 1. + * On 64bit platforms, we can set csum_unnecessary + * to true, but only if the skb is not shared. + */ +#if BITS_PER_LONG == 64 + if (!skb_shared(skb)) + udp_skb_scratch(skb)->csum_unnecessary = true; +#endif +} + static int udp_skb_truesize(struct sk_buff *skb) { return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS; @@ -1550,10 +1564,7 @@ static struct sk_buff *__first_packet_length(struct sock *sk, *total += skb->truesize; kfree_skb(skb); } else { - /* the csum related bits could be changed, refresh - * the scratch area - */ - udp_set_dev_scratch(skb); + udp_skb_csum_unnecessary_set(skb); break; } } |