Bug 2401431 (CVE-2025-39947)

Summary: CVE-2025-39947 kernel: net/mlx5e: Harden uplink netdev access against device unbind
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-10-04 08:03:00 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Harden uplink netdev access against device unbind

The function mlx5_uplink_netdev_get() gets the uplink netdevice
pointer from mdev->mlx5e_res.uplink_netdev. However, the netdevice can
be removed and its pointer cleared when unbound from the mlx5_core.eth
driver. This results in a NULL pointer, causing a kernel panic.

 BUG: unable to handle page fault for address: 0000000000001300
 at RIP: 0010:mlx5e_vport_rep_load+0x22a/0x270 [mlx5_core]
 Call Trace:
  <TASK>
  mlx5_esw_offloads_rep_load+0x68/0xe0 [mlx5_core]
  esw_offloads_enable+0x593/0x910 [mlx5_core]
  mlx5_eswitch_enable_locked+0x341/0x420 [mlx5_core]
  mlx5_devlink_eswitch_mode_set+0x17e/0x3a0 [mlx5_core]
  devlink_nl_eswitch_set_doit+0x60/0xd0
  genl_family_rcv_msg_doit+0xe0/0x130
  genl_rcv_msg+0x183/0x290
  netlink_rcv_skb+0x4b/0xf0
  genl_rcv+0x24/0x40
  netlink_unicast+0x255/0x380
  netlink_sendmsg+0x1f3/0x420
  __sock_sendmsg+0x38/0x60
  __sys_sendto+0x119/0x180
  do_syscall_64+0x53/0x1d0
  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Ensure the pointer is valid before use by checking it for NULL. If it
is valid, immediately call netdev_hold() to take a reference, and
preventing the netdevice from being freed while it is in use.
Comment 1 Alexander B 2025-10-06 17:55:17 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025100420-CVE-2025-39947-6872@gregkh/T