Description

In the Linux kernel, the following vulnerability has been resolved: tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR In the SIOCGIFHWADDR path, tap_ioctl() copies 16 bytes of an uninitialised on-stack struct sockaddr_storage to userspace via ifr_hwaddr, but netif_get_mac_address() only writes sa_family and dev->addr_len (6 for Ethernet) bytes, leaving sa_data[6..13] uninitialised. Those 8 trailing bytes leak kernel stack contents; SIOCGIFHWADDR on a macvtap chardev returns kernel .text and direct-map pointers, defeating KASLR. Initialise ss at declaration.

References 3

• git.kernel.org https://git.kernel.org/stable/c/05305e832be7b9d65b2b72caacf7d850b3942b2a
• git.kernel.org https://git.kernel.org/stable/c/719007c3492f0f1f9e9cdbed8ac45ba45bb13eeb
• git.kernel.org https://git.kernel.org/stable/c/bddc09212c24934643bd44fc794748d2bbb3b6cd

Remediation