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commit 0aaa81377c5a01f686bcdb8c7a6929a7bf330c68 upstream. Muyu Yu provided a POC where user root with CAP_NET_ADMIN can create a CAN frame modification rule that makes the data length code a higher value than the available CAN frame data size. In combination with a configured checksum calculation where the result is stored relatively to the end of the data (e.g. cgw_csum_xor_rel) the tail of the skb (e.g. frag_list pointer in skb_shared_info) can be rewritten which finally can cause a system crash. Michael Kubecek suggested to drop frames that have a DLC exceeding the available space after the modification process and provided a patch that can handle CAN FD frames too. Within this patch we also limit the length for the checksum calculations to the maximum of Classic CAN data length (8). CAN frames that are dropped by these additional checks are counted with the CGW_DELETED counter which indicates misconfigurations in can-gw rules. This fixes CVE-2019-3701. Reported-by: Muyu Yu <ieatmuttonchuan@gmail.com> Reported-by: Marcus Meissner <meissner@suse.de> Suggested-by: Michal Kubecek <mkubecek@suse.cz> Tested-by: Muyu Yu <ieatmuttonchuan@gmail.com> Tested-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Cc: linux-stable <stable@vger.kernel.org> # >= v3.2 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| af_can.c | ||
| af_can.h | ||
| bcm.c | ||
| gw.c | ||
| Kconfig | ||
| Makefile | ||
| proc.c | ||
| raw.c | ||