CVE-2024-57802

In the Linux kernel, the following vulnerability has been resolved:

netrom: check buffer length before accessing it

Syzkaller reports an uninit value read from ax25cmp when sending raw message through ieee802154 implementation.

===================================================== BUG: KMSAN: uninit-value in ax25cmp+0x3a5/0x460 net/ax25/ax25_addr.c:119 ax25cmp+0x3a5/0x460 net/ax25/ax25_addr.c:119 nr_dev_get+0x20e/0x450 net/netrom/nr_route.c:601 nr_route_frame+0x1a2/0xfc0 net/netrom/nr_route.c:774 nr_xmit+0x5a/0x1c0 net/netrom/nr_dev.c:144 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] raw_sendmsg+0x654/0xc10 net/ieee802154/socket.c:299 ieee802154_sock_sendmsg+0x91/0xc0 net/ieee802154/socket.c:96 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at: slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768 slab_alloc_node mm/slub.c:3478 [inline] kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560 __alloc_skb+0x318/0x740 net/core/skbuff.c:651 alloc_skb include/linux/skbuff.h:1286 [inline] alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6334 sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2780 sock_alloc_send_skb include/net/sock.h:1884 [inline] raw_sendmsg+0x36d/0xc10 net/ieee802154/socket.c:282 ieee802154_sock_sendmsg+0x91/0xc0 net/ieee802154/socket.c:96 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 0 PID: 5037 Comm: syz-executor166 Not tainted 6.7.0-rc7-syzkaller-00003-gfbafc3e621c3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023

This issue occurs because the skb buffer is too small, and it's actual allocation is aligned. This hides an actual issue, which is that nr_route_frame does not validate the buffer size before using it.

Fix this issue by checking skb->len before accessing any fields in skb->data.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

This vulnerability is rated as Moderate impact because exploitation requires local access and is constrained to causing a denial of service without compromising data integrity or confidentiality. Red Hat Enterprise Linux kernels do not enable support for the NetROM network protocol by default, preventing execution of the vulnerable routing code under standard installations. As a result, default configurations are not exposed unless a custom build with the affected protocol enabled is in use.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.