CVE-2026-97614

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

net: dsa: tag brcm: legacy FCS: request needed tailroom

The legacy FCS tagger calculates the CRC over skb->len bytes starting at skb->data. When a nonlinear skb reaches the tagger, this reads past the linear head into unrelated slab memory.

The tagger appends an Ethernet FCS but does not declare that tailroom. As a result, DSA leaves NETIF F SG and NETIF F FRAGLIST enabled on the user port, and nonlinear skbs can reach the CRC calculation.

Declare the required tailroom. DSA will then clear those features and the networking core will linearize skbs before the tagger runs.

A KASAN-enabled dsa loop test using this tagger reports:

BUG: KASAN: slab-out-of-bounds in crc32 le Read of size 1 at addr ffff8880397086c0 by task exp/135

Call Trace: crc32 le (lib/crc/crc32-main.c:38) brcm leg fcs tag xmit (net/dsa/tag brcm.c:343) dsa user xmit (net/dsa/user.c:942) dev hard start xmit (net/core/dev.c:3937) dev queue xmit (net/core/dev.c:4926) packet sendmsg (net/packet/af packet.c:3110) sys sendto (net/socket.c:2281)

The buggy address belongs to the object at ffff888039708400 which belongs to the cache skbuff small head of size 704 The buggy address is located 0 bytes to the right of allocated 704-byte region [ffff888039708400, ffff8880397086c0)