bpf: Fix stack-out-of-bounds write in devmap

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix stack-out-of-bounds write in devmap get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path.

Timeline

1. Mar 25, 2026, 10:27 AM UTCCVE published
2. Oct 15, 2026, 1:14 AM UTCRecord last updated

Affected versions

• Linux Linux

  From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in 88df604f0d16a692867582350ce3f2fcd22243f1; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in 5000e40acc8d0c36ab709662e32120986ac22e7e; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in 8a95fb9df1105b1618872c2846a6c01e3ba20b45; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in d2c31d8e03d05edc16656e5ffe187f0d1da763d7; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in 75d474702b2ba8b6bcb26eb3004dbc5e95ffd5d2; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in ca831567908fd3f73cf97d8a6c09a5054697a182; From aeea1b86f9363f3feabb496534d886f082a89f21 · fixed in b7bf516c3ecd9a2aae2dc2635178ab87b734fef1

• Linux Linux

  5.15

• KernelLinux

  From 5.15.0 · fixed in 5.15.203; From 5.16.0 · fixed in 6.1.167; From 6.2.0 · fixed in 6.6.130; From 6.7.0 · fixed in 6.12.77; From 6.13.0 · fixed in 6.18.17; From 6.19.0 · fixed in 6.19.7

References 7