2.6.36-stable review patch. If anyone has any objections, please let us know.
------------------
From: Eric Dumazet <eric.duma...@gmail.com>
[ Upstream commit f19872575ff7819a3723154657a497d9bca66b33 ]
Make sure sysctl_tcp_cookie_size is read once in
tcp_cookie_size_check(), or we might return an illegal value to caller
if sysctl_tcp_cookie_size is changed by another cpu.
Signed-off-by: Eric Dumazet <eric.duma...@gmail.com>
Cc: Ben Hutchings <bhutchi...@solarflare.com>
Cc: William Allen Simpson <william.allen.simp...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
net/ipv4/tcp_output.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -391,27 +391,30 @@ struct tcp_out_options {
*/
static u8 tcp_cookie_size_check(u8 desired)
{
- if (desired > 0) {
+ int cookie_size;
+
+ if (desired > 0)
/* previously specified */
return desired;
- }
- if (sysctl_tcp_cookie_size <= 0) {
+
+ cookie_size = ACCESS_ONCE(sysctl_tcp_cookie_size);
+ if (cookie_size <= 0)
/* no default specified */
return 0;
- }
- if (sysctl_tcp_cookie_size <= TCP_COOKIE_MIN) {
+
+ if (cookie_size <= TCP_COOKIE_MIN)
/* value too small, specify minimum */
return TCP_COOKIE_MIN;
- }
- if (sysctl_tcp_cookie_size >= TCP_COOKIE_MAX) {
+
+ if (cookie_size >= TCP_COOKIE_MAX)
/* value too large, specify maximum */
return TCP_COOKIE_MAX;
- }
- if (0x1 & sysctl_tcp_cookie_size) {
+
+ if (cookie_size & 1)
/* 8-bit multiple, illegal, fix it */
- return (u8)(sysctl_tcp_cookie_size + 0x1);
- }
- return (u8)sysctl_tcp_cookie_size;
+ cookie_size++;
+
+ return (u8)cookie_size;
}
/* Write previously computed TCP options to the packet.
_______________________________________________
stable mailing list
stable@linux.kernel.org
http://linux.kernel.org/mailman/listinfo/stable
