diff options
| author | Florian Westphal <fw@strlen.de> | 2018-02-19 01:24:15 +0100 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2018-11-27 16:18:53 +0100 |
| commit | f52ef5b1ce9c8c0214dcf58e28a579f7c4844cc3 (patch) | |
| tree | ede3c0da41327250b0363a2436a5255a78c30aaa | |
| parent | 513cef2c53c2b3846f6c571823412f514b6f66c7 (diff) | |
netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets
commit b71812168571fa55e44cdd0254471331b9c4c4c6 upstream.
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.
Change-Id: I20f5a2f604ed8a7767cfe4f0d4c4e73914f072b3
Reported-by: <syzbot+845a53d13171abf8bf29@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 203182a0a..d37753914 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2006,7 +2006,9 @@ 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; } @@ -2063,6 +2065,15 @@ 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; |