CVE-2024-26853 igc: avoid returning frame twice in XDP_REDIRECT

What is CVE-2024-26853?

CVE-2024-26853 is a critical memory corruption vulnerability in Linux kernel, published on 17 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

igc: avoid returning frame twice in XDP_REDIRECT

When a frame can not be transmitted in XDP_REDIRECT (e.g. due to a full queue), it is necessary to free it by calling xdp_return_frame_rx_napi.

However, this is the responsibility of the caller of the ndo_xdp_xmit (see for example bq_xmit_all in kernel/bpf/devmap.c) and thus calling it inside igc_xdp_xmit (which is the ndo_xdp_xmit of the igc driver) as well will lead to memory corruption.

In fact, bq_xmit_all expects that it can return all frames after the last successfully transmitted one. Therefore, break for the first not transmitted frame, but do not call xdp_return_frame_rx_napi in igc_xdp_xmit. This is equally implemented in other Intel drivers such as the igb.

There are two alternatives to this that were rejected: 1. Return num_frames as all the frames would have been transmitted and release them inside igc_xdp_xmit. While it might work technically, it is not what the return value is meant to represent (i.e. the number of SUCCESSFULLY transmitted packets). 2. Rework kernel/bpf/devmap.c and all drivers to support non-consecutively dropped packets. Besides being complex, it likely has a negative performance impact without a significant gain since it is anyway unlikely that the next frame can be transmitted if the previous one was dropped.

The memory corruption can be reproduced with the following script which leads to a kernel panic after a few seconds. It basically generates more traffic than a i225 NIC can transmit and pushes it via XDP_REDIRECT from a virtual interface to the physical interface where frames get dropped.

#!/bin/bash INTERFACE=enp4s0 INTERFACE_IDX=`cat /sys/class/net/$INTERFACE/ifindex`

sudo ip link add dev veth1 type veth peer name veth2 sudo ip link set up $INTERFACE sudo ip link set up veth1 sudo ip link set up veth2

cat << EOF > redirect.bpf.c

SEC("prog") int redirect(struct xdp_md *ctx) { return bpf_redirect($INTERFACE_IDX, 0); }

char _license[] SEC("license") = "GPL"; EOF clang -O2 -g -Wall -target bpf -c redirect.bpf.c -o redirect.bpf.o sudo ip link set veth2 xdp obj redirect.bpf.o

cat << EOF > pass.bpf.c

SEC("prog") int pass(struct xdp_md *ctx) { return XDP_PASS; }

char _license[] SEC("license") = "GPL"; EOF clang -O2 -g -Wall -target bpf -c pass.bpf.c -o pass.bpf.o sudo ip link set $INTERFACE xdp obj pass.bpf.o

cat << EOF > trafgen.cfg

{ /* Ethernet Header */ 0xe8, 0x6a, 0x64, 0x41, 0xbf, 0x46, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, const16(ETH_P_IP),

/* IPv4 Header */ 0b01000101, 0, # IPv4 version, IHL, TOS const16(1028), # IPv4 total length (UDP length + 20 bytes (IP header)) const16(2), # IPv4 ident 0b01000000, 0, # IPv4 flags, fragmentation off 64, # IPv4 TTL 17, # Protocol UDP csumip(14, 33), # IPv4 checksum

/* UDP Header */ 10, 0, 1, 1, # IP Src - adapt as needed 10, 0, 1, 2, # IP Dest - adapt as needed const16(6666), # UDP Src Port const16(6666), # UDP Dest Port const16(1008), # UDP length (UDP header 8 bytes + payload length) csumudp(14, 34), # UDP checksum

/* Payload */ fill('W', 1000), } EOF

sudo trafgen -i trafgen.cfg -b3000MB -o veth1 --cpp

Weakness: CWE-787

Which versions are affected by CVE-2024-26853?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-26853?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2024-26853 being exploited?

There is no known exploitation of CVE-2024-26853 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-59456, BELL-CVE-2024-26853, DEBIAN-CVE-2024-26853, GHSA-xh88-4pfp-fhr6, ROOT-OS-UBUNTU-2204-CVE-2024-26853, UBUNTU-CVE-2024-26853.