CVE-2026-23359bpf: Fix stack-out-of-bounds write in devmap

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/88df604f0d16a692867582350ce3f2fcd22243f1
• https://git.kernel.org/stable/c/5000e40acc8d0c36ab709662e32120986ac22e7e
• https://git.kernel.org/stable/c/8a95fb9df1105b1618872c2846a6c01e3ba20b45
• https://git.kernel.org/stable/c/d2c31d8e03d05edc16656e5ffe187f0d1da763d7
• https://git.kernel.org/stable/c/75d474702b2ba8b6bcb26eb3004dbc5e95ffd5d2
• https://git.kernel.org/stable/c/ca831567908fd3f73cf97d8a6c09a5054697a182
• https://git.kernel.org/stable/c/b7bf516c3ecd9a2aae2dc2635178ab87b734fef1
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html