Bug 2492459 (CVE-2026-53094) - CVE-2026-53094 kernel: bpf: Fix stale offload->prog pointer after constant blinding
Summary: CVE-2026-53094 kernel: bpf: Fix stale offload->prog pointer after constant bl...
Keywords:
Status: NEW
Alias: CVE-2026-53094
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-06-24 18:13 UTC by OSIDB Bzimport
Modified: 2026-06-25 10:01 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-06-24 18:13:13 UTC
In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix stale offload->prog pointer after constant blinding

When a dev-bound-only BPF program (BPF_F_XDP_DEV_BOUND_ONLY) undergoes
JIT compilation with constant blinding enabled (bpf_jit_harden >= 2),
bpf_jit_blind_constants() clones the program. The original prog is then
freed in bpf_jit_prog_release_other(), which updates aux->prog to point
to the surviving clone, but fails to update offload->prog.

This leaves offload->prog pointing to the freed original program. When
the network namespace is subsequently destroyed, cleanup_net() triggers
bpf_dev_bound_netdev_unregister(), which iterates ondev->progs and calls
__bpf_prog_offload_destroy(offload->prog). Accessing the freed prog
causes a page fault:

BUG: unable to handle page fault for address: ffffc900085f1038
Workqueue: netns cleanup_net
RIP: 0010:__bpf_prog_offload_destroy+0xc/0x80
Call Trace:
__bpf_offload_dev_netdev_unregister+0x257/0x350
bpf_dev_bound_netdev_unregister+0x4a/0x90
unregister_netdevice_many_notify+0x2a2/0x660
...
cleanup_net+0x21a/0x320

The test sequence that triggers this reliably is:

1. Set net.core.bpf_jit_harden=2 (echo 2 > /proc/sys/net/core/bpf_jit_harden)
2. Run xdp_metadata selftest, which creates a dev-bound-only XDP
   program on a veth inside a netns (./test_progs -t xdp_metadata)
3. cleanup_net -> page fault in __bpf_prog_offload_destroy

Dev-bound-only programs are unique in that they have an offload structure
but go through the normal JIT path instead of bpf_prog_offload_compile().
This means they are subject to constant blinding's prog clone-and-replace,
while also having offload->prog that must stay in sync.

Fix this by updating offload->prog in bpf_jit_prog_release_other(),
alongside the existing aux->prog update. Both are back-pointers to
the prog that must be kept in sync when the prog is replaced.

Comment 1 Mauro Matteo Cascella 2026-06-25 08:06:11 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062410-CVE-2026-53094-7b3d@gregkh/T


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