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| author | Florian Westphal <fw@strlen.de> | 2018-02-19 01:24:15 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-02-25 20:07:33 +0100 |
| commit | b71812168571fa55e44cdd0254471331b9c4c4c6 (patch) | |
| tree | 6dbae0f54e690041491407e6c0dee550fc67a60a /net | |
| parent | fc6a5d0601c5ac1d02f283a46f60b87b2033e5ca (diff) | |
| download | linux-b71812168571fa55e44cdd0254471331b9c4c4c6.tar.gz linux-b71812168571fa55e44cdd0254471331b9c4c4c6.tar.bz2 linux-b71812168571fa55e44cdd0254471331b9c4c4c6.zip | |
netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets
We need to make sure the offsets are not out of range of the
total size.
Also check that they are in ascending order.
The WARN_ON triggered by syzkaller (it sets panic_on_warn) is
changed to also bail out, no point in continuing parsing.
Briefly tested with simple ruleset of
-A INPUT --limit 1/s' --log
plus jump to custom chains using 32bit ebtables binary.
Reported-by: <syzbot+845a53d13171abf8bf29@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/bridge/netfilter/ebtables.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index 61f87879e389..254ef9f49567 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2060,7 +2060,9 @@ static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32, if (match_kern) match_kern->match_size = ret; - WARN_ON(type == EBT_COMPAT_TARGET && size_left); + if (WARN_ON(type == EBT_COMPAT_TARGET && size_left)) + return -EINVAL; + match32 = (struct compat_ebt_entry_mwt *) buf; } @@ -2116,6 +2118,15 @@ static int size_entry_mwt(struct ebt_entry *entry, const unsigned char *base, * * offsets are relative to beginning of struct ebt_entry (i.e., 0). */ + for (i = 0; i < 4 ; ++i) { + if (offsets[i] >= *total) + return -EINVAL; + if (i == 0) + continue; + if (offsets[i-1] > offsets[i]) + return -EINVAL; + } + for (i = 0, j = 1 ; j < 4 ; j++, i++) { struct compat_ebt_entry_mwt *match32; unsigned int size; |