CVE-2025-21680

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

pktgen: Avoid out-of-bounds access in get_imix_entries

Passing a sufficient amount of imix entries leads to invalid access to the pkt_dev->imix_entries array because of the incorrect boundary check.

UBSAN: array-index-out-of-bounds in net/core/pktgen.c:874:24 index 20 is out of range for type 'imix_pkt [20]' CPU: 2 PID: 1210 Comm: bash Not tainted 6.10.0-rc1 #121 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Call Trace: <TASK> dump_stack_lvl lib/dump_stack.c:117 __ubsan_handle_out_of_bounds lib/ubsan.c:429 get_imix_entries net/core/pktgen.c:874 pktgen_if_write net/core/pktgen.c:1063 pde_write fs/proc/inode.c:334 proc_reg_write fs/proc/inode.c:346 vfs_write fs/read_write.c:593 ksys_write fs/read_write.c:644 do_syscall_64 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:130

Found by Linux Verification Center (linuxtesting.org) with SVACE.

[ fp: allow to fill the array completely; minor changelog cleanup ]

This vulnerability is rated as Moderate because exploitation requires local access and the ability to interact with the kernel packet generator's procfs control interface, which is typically restricted to privileged users. The pktgen module is an optional network testing utility and is not loaded by default in standard Red Hat deployments. Consequently, systems are only exposed if the module is explicitly loaded and configured by an administrator.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.