If received skb in batadv_v_elp_packet_recv or batadv_v_ogm_packet_recv is either cloned or non linearized then its data buffer will be reallocated by batadv_check_management_packet when skb_cow or skb_linearize get called. Thus geting ethernet header address inside skb data buffer before batadv_check_management_packet had any chance to reallocate it could lead to the following kernel panic:

Unable to handle kernel paging request at virtual address ffffff8020ab069a Mem abort info: ESR = 0x96000007 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x07: level 3 translation fault Data abort info: ISV = 0, ISS = 0x00000007 CM = 0, WnR = 0 swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000040f45000 [ffffff8020ab069a] pgd=180000007fffa003, p4d=180000007fffa003, pud=180000007fffa003, pmd=180000007fefe003, pte=0068000020ab0706 Internal error: Oops: 96000007 [#1] SMP Modules linked in: ahci_mvebu libahci_platform libahci dvb_usb_af9035 dvb_usb_dib0700 dib0070 dib7000m dibx000_common ath11k_pci ath10k_pci ath10k_core mwl8k_new nf_nat_sip nf_conntrack_sip xhci_plat_hcd xhci_hcd nf_nat_pptp nf_conntrack_pptp at24 sbsa_gwdt CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.15.42-00066-g3242268d425c-dirty #550 Hardware name: A8k (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : batadv_is_my_mac+0x60/0xc0 lr : batadv_v_ogm_packet_recv+0x98/0x5d0 sp : ffffff8000183820 x29: ffffff8000183820 x28: 0000000000000001 x27: ffffff8014f9af00 x26: 0000000000000000 x25: 0000000000000543 x24: 0000000000000003 x23: ffffff8020ab0580 x22: 0000000000000110 x21: ffffff80168ae880 x20: 0000000000000000 x19: ffffff800b561000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 00dc098924ae0032 x14: 0f0405433e0054b0 x13: ffffffff00000080 x12: 0000004000000001 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : 0000000000000000 x7 : ffffffc076dae000 x6 : ffffff8000183700 x5 : ffffffc00955e698 x4 : ffffff80168ae000 x3 : ffffff80059cf000 x2 : ffffff800b561000 x1 : ffffff8020ab0696 x0 : ffffff80168ae880 Call trace: batadv_is_my_mac+0x60/0xc0 batadv_v_ogm_packet_recv+0x98/0x5d0 batadv_batman_skb_recv+0x1b8/0x244 __netif_receive_skb_core.isra.0+0x440/0xc74 __netif_receive_skb_one_core+0x14/0x20 netif_receive_skb+0x68/0x140 br_pass_frame_up+0x70/0x80 br_handle_frame_finish+0x108/0x284 br_handle_frame+0x190/0x250 __netif_receive_skb_core.isra.0+0x240/0xc74 __netif_receive_skb_list_core+0x6c/0x90 netif_receive_skb_list_internal+0x1f4/0x310 napi_complete_done+0x64/0x1d0 gro_cell_poll+0x7c/0xa0 __napi_poll+0x34/0x174 net_rx_action+0xf8/0x2a0 _stext+0x12c/0x2ac run_ksoftirqd+0x4c/0x7c smpboot_thread_fn+0x120/0x210 kthread+0x140/0x150 ret_from_fork+0x10/0x20 Code: f9403844 eb03009f 54fffee1 f94

Thus ethernet header address should only be fetched after batadv_check_management_packet has been called.

Fixes: 0da0035942d4 ("batman-adv: OGMv2 - add basic infrastructure") Signed-off-by: Remi Pommarel repk@triplefau.lt --- net/batman-adv/bat_v_elp.c | 3 ++- net/batman-adv/bat_v_ogm.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c index acff565849ae..1d704574e6bf 100644 --- a/net/batman-adv/bat_v_elp.c +++ b/net/batman-adv/bat_v_elp.c @@ -505,7 +505,7 @@ int batadv_v_elp_packet_recv(struct sk_buff *skb, struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface); struct batadv_elp_packet *elp_packet; struct batadv_hard_iface *primary_if; - struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb); + struct ethhdr *ethhdr; bool res; int ret = NET_RX_DROP;

@@ -513,6 +513,7 @@ int batadv_v_elp_packet_recv(struct sk_buff *skb, if (!res) goto free_skb;

+ ethhdr = eth_hdr(skb); if (batadv_is_my_mac(bat_priv, ethhdr->h_source)) goto free_skb;

diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index e710e9afe78f..84eac41d4658 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -985,7 +985,7 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb, { struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface); struct batadv_ogm2_packet *ogm_packet; - struct ethhdr *ethhdr = eth_hdr(skb); + struct ethhdr *ethhdr; int ogm_offset; u8 *packet_pos; int ret = NET_RX_DROP; @@ -999,6 +999,7 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb, if (!batadv_check_management_packet(skb, if_incoming, BATADV_OGM2_HLEN)) goto free_skb;

+ ethhdr = eth_hdr(skb); if (batadv_is_my_mac(bat_priv, ethhdr->h_source)) goto free_skb;