[2.6.24][BUG] Compact code broken?

[Luca Tettamanti <kronos.it@gmail.com>]

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Hello,
I'm testing a 64bit kernel on my machine and I've found an issue with
iptables (32 bit). Kernel is git current (9418d5dc).

I'm unable to add any rule to the filter table, with kernel returning
EFAULT:

socket(PF_INET, SOCK_RAW, IPPROTO_RAW)  = 3
getsockopt(3, SOL_IP, 0x40 /* IP_??? */, "filter\0\377@\212r\200\377\377\377\3778 \230)\0\201\377"..., [84]) = 0
getsockopt(3, SOL_IP, 0x41 /* IP_??? */, "filter\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., [656]) = 0
setsockopt(3, SOL_IP, 0x40 /* IP_??? */, "filter\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 860) = -1 EFAULT (Bad address)
write(2, "iptables: Bad address\n", 22) = 22

With a bit of printk I've tracked it to the first copy_from_user in
compat_do_replace:

compat_do_replace:1859: user = ffffffff883cc370, len = 860
compat_do_replace:1864: copy_from_user = 92

Userspace reports:

iptc_init: valid_hooks=0x0000000e, num_entries=4, size=620
cache_add_entry: entering...0:0 new builtin chain: 0x8055910 (rules=0x8055960)
0:0 normal rule: 0x8055980: standard, verdict=-2
cache_add_entry: entering...1:148 new builtin chain: 0x8055a40 (rules=0x8055a90)
iptcc_delete_rule: deleting rule 0x8055980 (offset 0)
1:148 normal rule: 0x8055980: standard, verdict=-2
cache_add_entry: entering...2:296 new builtin chain: 0x8055ab0 (rules=0x8055b00)
iptcc_delete_rule: deleting rule 0x8055980 (offset 148)
2:296 normal rule: 0x8055980: standard, verdict=-2
cache_add_entry: entering...3:444: end of table:
iptcc_delete_rule: deleting rule 0x8055980 (offset 296)
iptcc_compile_chain_offsets: INPUT: chain_head 0, offset=0
iptcc_compile_chain_offsets: rule 0, offset=0, index=0
iptcc_compile_chain_offsets: INPUT; chain_foot 1, offset=148, index=1
iptcc_compile_chain_offsets: FORWARD: chain_head 2, offset=296
iptcc_compile_chain_offsets: FORWARD; chain_foot 2, offset=296, index=2
iptcc_compile_chain_offsets: OUTPUT: chain_head 3, offset=444
iptcc_compile_chain_offsets: OUTPUT; chain_foot 3, offset=444, index=3
iptc_commit: num_entries=5, size=768, num_counters=4
iptc_commit: repl=0x8055be0 <--- this is the argument of setsockopt
iptables: Bad address

I'm also attaching the 2 blobs created by iptables.

The test command was:
iptables -A INPUT -s 123.123.123.132 -i eth0 -j DROP

32 bit userspace with 32 kernel works fine; I'm unable to test with 64
bit userspace (it would require a big surgery on my existing 32 bit
installation).

Luca
-- 
"In linea di principio sarei indifferente al natale, se solo il natale
 ricambiasse la cortesia e mi lasciasse in pace." -- Marco d'Itri

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