path: root/include/linux/netfilter_bridge/ebtables.h
diff options
authorFlorian Westphal <fw@strlen.de>2022-08-20 17:38:37 +0200
committerFlorian Westphal <fw@strlen.de>2022-08-23 18:23:15 +0200
commit7997eff82828304b780dc0a39707e1946d6f1ebf (patch)
tree74a5822a96dd4a2a66ce0d0fbbc92d27d89aa111 /include/linux/netfilter_bridge/ebtables.h
parentnet: dsa: don't dereference NULL extack in dsa_slave_changeupper() (diff)
netfilter: ebtables: reject blobs that don't provide all entry points
Harshit Mogalapalli says: In ebt_do_table() function dereferencing 'private->hook_entry[hook]' can lead to NULL pointer dereference. [..] Kernel panic: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] [..] RIP: 0010:ebt_do_table+0x1dc/0x1ce0 Code: 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 5c 16 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 6c df 08 48 8d 7d 2c 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 88 [..] Call Trace: nf_hook_slow+0xb1/0x170 __br_forward+0x289/0x730 maybe_deliver+0x24b/0x380 br_flood+0xc6/0x390 br_dev_xmit+0xa2e/0x12c0 For some reason ebtables rejects blobs that provide entry points that are not supported by the table, but what it should instead reject is the opposite: blobs that DO NOT provide an entry point supported by the table. t->valid_hooks is the bitmask of hooks (input, forward ...) that will see packets. Providing an entry point that is not support is harmless (never called/used), but the inverse isn't: it results in a crash because the ebtables traverser doesn't expect a NULL blob for a location its receiving packets for. Instead of fixing all the individual checks, do what iptables is doing and reject all blobs that differ from the expected hooks. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to '')
1 files changed, 0 insertions, 4 deletions
diff --git a/include/linux/netfilter_bridge/ebtables.h b/include/linux/netfilter_bridge/ebtables.h
index a13296d6c7ce..fd533552a062 100644
--- a/include/linux/netfilter_bridge/ebtables.h
+++ b/include/linux/netfilter_bridge/ebtables.h
@@ -94,10 +94,6 @@ struct ebt_table {
struct ebt_replace_kernel *table;
unsigned int valid_hooks;
rwlock_t lock;
- /* e.g. could be the table explicitly only allows certain
- * matches, targets, ... 0 == let it in */
- int (*check)(const struct ebt_table_info *info,
- unsigned int valid_hooks);
/* the data used by the kernel */
struct ebt_table_info *private;
struct nf_hook_ops *ops;