Medium · published June 24, 2026
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.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 5.4.103, < 5.5 | 5.5 |
| linux/linux_kernel | ≥ 5.10.21, < 5.11 | 5.11 |
| linux/linux_kernel | ≥ 5.11.4, < 6.18.34 | 6.18.34 |
| linux/linux_kernel | ≥ 6.19, < 7.0.11 | 7.0.11 |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |