medium CVSS 5.5 EPSS <0.1%

CVE-2023-52784·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: bonding: stop the device in bond_setup_by_slave() Commit 9eed321cde22 ("net: lapbether: only support ethernet devices") has been able to keep syzbot away from net/lapb, until today. In the following splat [1], the issue is that a lapbether device has been created on a bonding device without members. Then adding a non ARPHRD_ETHER member forced the bonding master to change its type. The fix is to make sure we call dev_close() in bond_setup_by_slave() so that the potential linked lapbether devices (or any other devices having assumptions on the physical device) are removed. A similar bug has been addressed in commit 40baec225765 ("bonding: fix panic on non-ARPHRD_ETHER enslave failure") [1] skbuff: skb_under_panic: text:ffff800089508810 len:44 put:40 head:ffff0000c78e7c00 data:ffff0000c78e7bea tail:0x16 end:0x140 dev:bond0 kernel BUG at net/core/skbuff.c:192 ! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 6007 Comm: syz-executor383 Not tainted 6.6.0-rc3-syzkaller-gbf6547d8715b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : skb_panic net/core/skbuff.c:188 [inline] pc : skb_under_panic+0x13c/0x140 net/core/skbuff.c:202 lr : skb_panic net/core/skbuff.c:188 [inline] lr : skb_under_panic+0x13c/0x140 net/core/skbuff.c:202 sp : ffff800096a06aa0 x29: ffff800096a06ab0 x28: ffff800096a06ba0 x27: dfff800000000000 x26: ffff0000ce9b9b50 x25: 0000000000000016 x24: ffff0000c78e7bea x23: ffff0000c78e7c00 x22: 000000000000002c x21: 0000000000000140 x20: 0000000000000028 x19: ffff800089508810 x18: ffff800096a06100 x17: 0000000000000000 x16: ffff80008a629a3c x15: 0000000000000001 x14: 1fffe00036837a32 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000201 x10: 0000000000000000 x9 : cb50b496c519aa00 x8 : cb50b496c519aa00 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff800096a063b8 x4 : ffff80008e280f80 x3 : ffff8000805ad11c x2 : 0000000000000001 x1 : 0000000100000201 x0 : 0000000000000086 Call trace: skb_panic net/core/skbuff.c:188 [inline] skb_under_panic+0x13c/0x140 net/core/skbuff.c:202 skb_push+0xf0/0x108 net/core/skbuff.c:2446 ip6gre_header+0xbc/0x738 net/ipv6/ip6_gre.c:1384 dev_hard_header include/linux/netdevice.h:3136 [inline] lapbeth_data_transmit+0x1c4/0x298 drivers/net/wan/lapbether.c:257 lapb_data_transmit+0x8c/0xb0 net/lapb/lapb_iface.c:447 lapb_transmit_buffer+0x178/0x204 net/lapb/lapb_out.c:149 lapb_send_control+0x220/0x320 net/lapb/lapb_subr.c:251 __lapb_disconnect_request+0x9c/0x17c net/lapb/lapb_iface.c:326 lapb_device_event+0x288/0x4e0 net/lapb/lapb_iface.c:492 notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461 call_netdevice_notifiers_info net/core/dev.c:1970 [inline] call_netdevice_notifiers_extack net/core/dev.c:2008 [inline] call_netdevice_notifiers net/core/dev.c:2022 [inline] __dev_close_many+0x1b8/0x3c4 net/core/dev.c:1508 dev_close_many+0x1e0/0x470 net/core/dev.c:1559 dev_close+0x174/0x250 net/core/dev.c:1585 lapbeth_device_event+0x2e4/0x958 drivers/net/wan/lapbether.c:466 notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461 call_netdevice_notifiers_info net/core/dev.c:1970 [inline] call_netdevice_notifiers_extack net/core/dev.c:2008 [inline] call_netdevice_notifiers net/core/dev.c:2022 [inline] __dev_close_many+0x1b8/0x3c4 net/core/dev.c:1508 dev_close_many+0x1e0/0x470 net/core/dev.c:1559 dev_close+0x174/0x250 net/core/dev.c:1585 bond_enslave+0x2298/0x30cc drivers/net/bonding/bond_main.c:2332 bond_do_ioctl+0x268/0xc64 drivers/net/bonding/bond_main.c:4539 dev_ifsioc+0x754/0x9ac dev_ioctl+0x4d8/0xd34 net/core/dev_ioctl.c:786 sock_do_ioctl+0x1d4/0x2d0 net/socket.c:1217 sock_ioctl+0x4e8/0x834 net/socket.c:1322 vfs_ioctl fs/ioctl.c:51 [inline] __do_ ---truncated---

Severity
medium
Software
Kernel
Fixed in
6.6.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — in the bottom 1% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

From: 6.6

Until: 6.6.3

Fixed in: 6.6.3

How to fix this CVE

Update your Linux kernel to version 6.6.3 or later to resolve a critical bonding driver issue that causes kernel panic when non-Ethernet devices are enslaved to a bonding interface. This fix ensures that dependent network devices (such as LAPB Ethernet devices) are properly cleaned up when the bonding device type changes, preventing memory corruption and system crashes.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` — if it shows 6.6.0 through 6.6.2, you are vulnerable.
  2. Step 2: List all bonding interfaces with `cat /proc/net/bonding/bond* 2>/dev/null` — verify if non-Ethernet devices are enslaved.
  3. Step 3: Search system logs for skb_under_panic errors with `journalctl -b | grep -i 'skb_under_panic\|BUG at net/core/skbuff'`.
  4. Step 4: After updating, verify the fix with `uname -r` and confirm the kernel version is 6.6.3 or higher, then reboot if required.

FAQ

What is CVE-2023-52784?

This vulnerability exists in the Linux kernel bonding driver where adding non-Ethernet devices to a bonding interface without proper cleanup causes a kernel panic and memory corruption via skb buffer underflow.

Is CVE-2023-52784 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and there are no public exploits available. Exploitation typically requires local access to manipulate bonding configuration.

What versions of Kernel are affected by CVE-2023-52784?

Linux kernel versions 6.6.0 through 6.6.2 are vulnerable. The fix is included in kernel 6.6.3 and later releases.

How do I check if my server is vulnerable to CVE-2023-52784?

Run `uname -r` and check if the output shows version 6.6.0, 6.6.1, or 6.6.2. If so, your system is vulnerable and requires a kernel update.

Does Defensia detect CVE-2023-52784?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2023-52784 will appear in your dashboard with remediation steps.

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References

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