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tcp: Fix data-races around sysctl knobs related to SYN option.

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[ Upstream commit 3666f666e99600518ab20982af04a078bbdad277 ]

While reading these knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

  - tcp_sack
  - tcp_window_scaling
  - tcp_timestamps

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kuniyuki Iwashima
2022-07-18 10:26:44 -07:00
committed by Greg Kroah-Hartman
parent fcaef69c79
commit ffc388f6f0
5 changed files with 16 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
net/ipv4/tcp_input.c
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@@ -4007,7 +4007,7 @@ void tcp_parse_options(const struct net *net,
break;
case TCPOPT_WINDOW:
if (opsize == TCPOLEN_WINDOW && th->syn &&
!estab && net->ipv4.sysctl_tcp_window_scaling) {
!estab && READ_ONCE(net->ipv4.sysctl_tcp_window_scaling)) {
__u8 snd_wscale = *(__u8 *)ptr;
opt_rx->wscale_ok = 1;
if (snd_wscale > TCP_MAX_WSCALE) {
@@ -4023,7 +4023,7 @@ void tcp_parse_options(const struct net *net,
case TCPOPT_TIMESTAMP:
if ((opsize == TCPOLEN_TIMESTAMP) &&
((estab && opt_rx->tstamp_ok) ||
(!estab && net->ipv4.sysctl_tcp_timestamps))) {
(!estab && READ_ONCE(net->ipv4.sysctl_tcp_timestamps)))) {
opt_rx->saw_tstamp = 1;
opt_rx->rcv_tsval = get_unaligned_be32(ptr);
opt_rx->rcv_tsecr = get_unaligned_be32(ptr + 4);
@@ -4031,7 +4031,7 @@ void tcp_parse_options(const struct net *net,
break;
case TCPOPT_SACK_PERM:
if (opsize == TCPOLEN_SACK_PERM && th->syn &&
!estab && net->ipv4.sysctl_tcp_sack) {
!estab && READ_ONCE(net->ipv4.sysctl_tcp_sack)) {
opt_rx->sack_ok = TCP_SACK_SEEN;
tcp_sack_reset(opt_rx);
}