diff options
| author | Oliver Hartkopp | 2019-12-07 19:34:18 +0100 |
|---|---|---|
| committer | Marc Kleine-Budde | 2020-01-02 15:34:27 +0100 |
| commit | e7153bf70c3496bac00e7e4f395bb8d8394ac0ea (patch) | |
| tree | 916e307b02f8f88d6db4ce4878104be0f4cd31f4 | |
| parent | 93bdc0eb0b4bb5e7094fd4a95f4a394e4a927e09 (diff) | |
can: can_dropped_invalid_skb(): ensure an initialized headroom in outgoing CAN sk_buffs
KMSAN sysbot detected a read access to an untinitialized value in the
headroom of an outgoing CAN related sk_buff. When using CAN sockets this
area is filled appropriately - but when using a packet socket this
initialization is missing.
The problematic read access occurs in the CAN receive path which can
only be triggered when the sk_buff is sent through a (virtual) CAN
interface. So we check in the sending path whether we need to perform
the missing initializations.
Fixes: d3b58c47d330d ("can: replace timestamp as unique skb attribute")
Reported-by: syzbot+b02ff0707a97e4e79ebb@syzkaller.appspotmail.com
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: linux-stable <stable@vger.kernel.org> # >= v4.1
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
| -rw-r--r-- | include/linux/can/dev.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index 9b3c720a31b1..5e3d45525bd3 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -18,6 +18,7 @@ #include <linux/can/error.h> #include <linux/can/led.h> #include <linux/can/netlink.h> +#include <linux/can/skb.h> #include <linux/netdevice.h> /* @@ -91,6 +92,36 @@ struct can_priv { #define get_can_dlc(i) (min_t(__u8, (i), CAN_MAX_DLC)) #define get_canfd_dlc(i) (min_t(__u8, (i), CANFD_MAX_DLC)) +/* Check for outgoing skbs that have not been created by the CAN subsystem */ +static inline bool can_skb_headroom_valid(struct net_device *dev, + struct sk_buff *skb) +{ + /* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */ + if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv))) + return false; + + /* af_packet does not apply CAN skb specific settings */ + if (skb->ip_summed == CHECKSUM_NONE) { + /* init headroom */ + can_skb_prv(skb)->ifindex = dev->ifindex; + can_skb_prv(skb)->skbcnt = 0; + + skb->ip_summed = CHECKSUM_UNNECESSARY; + + /* preform proper loopback on capable devices */ + if (dev->flags & IFF_ECHO) + skb->pkt_type = PACKET_LOOPBACK; + else + skb->pkt_type = PACKET_HOST; + + skb_reset_mac_header(skb); + skb_reset_network_header(skb); + skb_reset_transport_header(skb); + } + + return true; +} + /* Drop a given socketbuffer if it does not contain a valid CAN frame. */ static inline bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb) @@ -108,6 +139,9 @@ static inline bool can_dropped_invalid_skb(struct net_device *dev, } else goto inval_skb; + if (!can_skb_headroom_valid(dev, skb)) + goto inval_skb; + return false; inval_skb: |