5c04da55c7
syzkaller reports splat:
------------[ cut here ]------------
Buffer overflow detected (80 < 137)!
Call Trace:
do_ebt_get_ctl+0x2b4/0x790 net/bridge/netfilter/ebtables.c:2317
nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116
ip_getsockopt net/ipv4/ip_sockglue.c:1778 [inline]
caused by a copy-to-user with a too-large "*len" value.
This adds a argument check on *len just like in the non-compat version
of the handler.
Before the "Fixes" commit, the reproducer fails with -EINVAL as
expected:
1. core calls the "compat" getsockopt version
2. compat getsockopt version detects the *len value is possibly
in 64-bit layout (*len != compat_len)
3. compat getsockopt version delegates everything to native getsockopt
version
4. native getsockopt rejects invalid *len
-> compat handler only sees len == sizeof(compat_struct) for GET_ENTRIES.
After the refactor, event sequence is:
1. getsockopt calls "compat" version (len != native_len)
2. compat version attempts to copy *len bytes, where *len is random
value from userspace
Fixes: fc66de8e16ec ("netfilter/ebtables: clean up compat {get, set}sockopt handling")
Reported-by: syzbot+5accb5c62faa1d346480@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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| .. | ||
| ebt_802_3.c | ||
| ebt_among.c | ||
| ebt_arp.c | ||
| ebt_arpreply.c | ||
| ebt_dnat.c | ||
| ebt_ip6.c | ||
| ebt_ip.c | ||
| ebt_limit.c | ||
| ebt_log.c | ||
| ebt_mark_m.c | ||
| ebt_mark.c | ||
| ebt_nflog.c | ||
| ebt_pkttype.c | ||
| ebt_redirect.c | ||
| ebt_snat.c | ||
| ebt_stp.c | ||
| ebt_vlan.c | ||
| ebtable_broute.c | ||
| ebtable_filter.c | ||
| ebtable_nat.c | ||
| ebtables.c | ||
| Kconfig | ||
| Makefile | ||
| nf_conntrack_bridge.c | ||
| nf_log_bridge.c | ||
| nft_meta_bridge.c | ||
| nft_reject_bridge.c | ||