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@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
net/bridge/netfilter/ebtables.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 02c4b409d317..3f536c7a3354 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2053,7 +2053,9 @@ 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;
}
@@ -2109,6 +2111,15 @@ 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;
--
2.16.1
--
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