Comment 3 for bug 152741

Revision history for this message
Brian Murray (brian-murray) wrote :

I found a patch in the lkml thread at http://<email address hidden>/msg213559.html. This is essentially a one line patch to the kernel that has been well tested since it is Hardy also. I think it'd be worthwhile to get this fixed in Gutsy. The patch follows:

Problem spotted by Denys Fedoryshchenko

Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>

--- linux-2.6.22/drivers/char/random.c 2007-10-01 10:18:42.000000000 +0200
+++ linux-2.6.22-ed/drivers/char/random.c 2007-10-01 21:47:58.000000000
+0200
@@ -1550,11 +1550,13 @@ __u32 secure_tcp_sequence_number(__be32
         * As close as possible to RFC 793, which
         * suggests using a 250 kHz clock.
         * Further reading shows this assumes 2 Mb/s networks.
- * For 10 Gb/s Ethernet, a 1 GHz clock is appropriate.
- * That's funny, Linux has one built in! Use it!
- * (Networks are faster now - should this be increased?)
+ * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
+ * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
+ * we also need to limit the resolution so that the u32 seq
+ * overlaps less than one time per MSL (2 minutes).
+ * Choosing a clock of 64 ns period is OK. (period of 274 s)
         */
- seq += ktime_get_real().tv64;
+ seq += ktime_get_real().tv64 >> 6;
 #if 0
        printk("init_seq(%lx, %lx, %d, %d) = %d\n",
               saddr, daddr, sport, dport, seq);