CVE-2025-21855

/// Technical description

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

ibmvnic: Don't reference skb after sending to VIOS

Previously, after successfully flushing the xmit buffer to VIOS,

the tx_bytes stat was incremented by the length of the skb.

It is invalid to access the skb memory after sending the buffer to

the VIOS because, at any point after sending, the VIOS can trigger

an interrupt to free this memory. A race between reading skb->len

and freeing the skb is possible (especially during LPM) and will

result in use-after-free:

==================================================================

BUG: KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic]

Read of size 4 at addr c00000024eb48a70 by task hxecom/14495

<...>

Call Trace:

[c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable)

[c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0

[c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8

[c000000118f66f00] [c0000000006f28

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References