Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim The root cause of this bug is that when 'bpf_link_put' reduces the refcount of 'shim_link->link.link' to zero, the resource is considered released but may still be referenced via 'tr->progs_hlist' in 'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in 'bpf_shim_tramp_link_release' is deferred. During this window, another process can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'. Based on Martin KaFai Lau's suggestions, I have created a simple patch. To fix this: Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'. Only increment the refcount if it is not already zero. Testing: I verified the fix by adding a delay in 'bpf_shim_tramp_link_release' to make the bug easier to trigger: static void bpf_shim_tramp_link_release(struct bpf_link link) { / ... */ if (!shim_link->trampoline) return; + msleep(100); WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline, NULL)); bpf_trampoline_put(shim_link->trampoline); } Before the patch, running a PoC easily reproduced the crash(almost 100%) with a call trace similar to KaiyanM's report. After the patch, the bug no longer occurs even after millions of iterations.
Mitigation
Minimal update. May introduce new vulnerabilities or breaking changes.
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 rpm rhel9 | | - | - |
rpm rhel9 | | - | - |
 debian 12 | | =6.1.106-1 || =6.1.106-2 || =6.1.106-3 || =6.1.112-1 || =6.1.115-1 || =6.1.119-1 || =6.1.123-1 || =6.1.124-1 || =6.1.128-1 || =6.1.129-1 || =6.1.133-1 || =6.1.135-1 || =6.1.137-1 || =6.1.139-1 || =6.1.140-1 || =6.1.147-1 || =6.1.148-1 || =6.1.153-1 || =6.1.158-1 || =6.1.159-1 || =6.1.162-1 || =6.1.164-1 || =6.1.27-1 || =6.1.37-1 || =6.1.38-1 || =6.1.38-2 || =6.1.38-2~bpo11+1 || =6.1.38-3 || =6.1.38-4 || =6.1.38-4~bpo11+1 || =6.1.52-1 || =6.1.55-1 || =6.1.55-1~bpo11+1 || =6.1.64-1 || =6.1.66-1 || =6.1.67-1 || =6.1.69-1 || =6.1.69-1~bpo11+1 || =6.1.76-1 || =6.1.76-1~bpo11+1 || =6.1.82-1 || =6.1.85-1 || =6.1.90-1 || =6.1.90-1~bpo11+1 || =6.1.94-1 || =6.1.94-1~bpo11+1 || =6.1.98-1 || =6.1.99-1 || >=0 <6.1.170-1 | 6.1.170-1 |
debian 13 | | =6.12.38-1 || =6.12.41-1 || =6.12.43-1 || =6.12.43-1~bpo12+1 || =6.12.48-1 || =6.12.57-1 || =6.12.57-1~bpo12+1 || =6.12.63-1 || =6.12.63-1~bpo12+1 || =6.12.69-1 || =6.12.69-1~bpo12+1 || =6.12.73-1 || =6.12.73-1~bpo12+1 || =6.12.74-1 || =6.12.74-2 || =6.12.74-2~bpo12+1 || =6.12.85-1~bpo12+1 || >=0 <6.12.85-1 | 6.12.85-1 |
debian 14 | | =6.12.38-1 || =6.12.41-1 || =6.12.43-1 || =6.12.43-1~bpo12+1 || =6.12.48-1 || =6.12.57-1 || =6.12.57-1~bpo12+1 || =6.12.63-1 || =6.12.63-1~bpo12+1 || =6.12.69-1 || =6.12.69-1~bpo12+1 || =6.12.73-1 || =6.12.73-1~bpo12+1 || =6.12.74-1 || =6.12.74-2 || =6.12.74-2~bpo12+1 || =6.12.85-1 || =6.12.85-1~bpo12+1 || =6.13.10-1~exp1 || =6.13.11-1~exp1 || =6.13.2-1~exp1 || =6.13.3-1~exp1 || =6.13.4-1~exp1 || =6.13.5-1~exp1 || =6.13.6-1~exp1 || =6.13.7-1~exp1 || =6.13.8-1~exp1 || =6.13.9-1~exp1 || =6.13~rc6-1~exp1 || =6.13~rc7-1~exp1 || =6.14.3-1~exp1 || =6.14.5-1~exp1 || =6.14.6-1~exp1 || =6.15-1~exp1 || =6.15.1-1~exp1 || =6.15.2-1~exp1 || =6.15.3-1~exp1 || =6.15.4-1~exp1 || =6.15.5-1~exp1 || =6.15.6-1~exp1 || =6.15~rc7-1~exp1 || =6.16-1~exp1 || =6.16.1-1~exp1 || =6.16.10-1 || =6.16.11-1 || =6.16.12-1 || =6.16.12-1~bpo13+1 || =6.16.12-2 || =6.16.3-1 || =6.16.3-1~bpo13+1 || =6.16.5-1 || =6.16.6-1 || =6.16.7-1 || =6.16.8-1 || =6.16.9-1 || =6.16~rc7-1~exp1 || =6.17.10-1 || =6.17.11-1 || =6.17.12-1 || =6.17.13-1 || =6.17.13-1~bpo13+1 || =6.17.2-1~exp1 || =6.17.5-1~exp1 || =6.17.6-1 || =6.17.7-1 || =6.17.7-2 || =6.17.8-1 || =6.17.8-1~bpo13+1 || =6.17.9-1 || =6.18.1-1~exp1 || =6.18.10-1 || =6.18.12-1 || =6.18.12-1~bpo13+1 || =6.18.13-1 || =6.18.14-1 || =6.18.15-1 || =6.18.15-1~bpo13+1 || =6.18.2-1~exp1 || =6.18.3-1 || =6.18.5-1 || =6.18.5-1~bpo13+1 || =6.18.8-1 || =6.18.9-1 || =6.18.9-1~bpo13+1 || =6.18~rc4-1~exp1 || =6.18~rc4-1~exp2 || =6.18~rc5-1~exp1 || =6.18~rc6-1~exp1 || =6.18~rc7-1~exp1 || =6.19-1~exp1 || =6.19.2-1~exp1 || =6.19.3-1~exp1 || =6.19.4-1~exp1 || =6.19.5-1~exp1 || =6.19.6-1 || =6.19.6-2 || =6.19.6-2~bpo13+1 || =6.19.8-1~bpo13+1 || =6.19~rc4-1~exp1 || =6.19~rc5-1~exp1 || =6.19~rc6-1~exp1 || =6.19~rc7-1~exp1 || =6.19~rc8-1~exp1 || >=0 <6.19.8-1 | 6.19.8-1 |
rpm rhel10 | | - | - |
debian 11 | | =6.1.106-3~deb11u1 || =6.1.106-3~deb11u2 || =6.1.106-3~deb11u3 || =6.1.112-1~deb11u1 || =6.1.119-1~deb11u1 || =6.1.128-1~deb11u1 || =6.1.129-1~deb11u1 || =6.1.137-1~deb11u1 || =6.1.140-1~deb11u1 || =6.1.147-1~deb11u1 || =6.1.148-1~deb11u1 || =6.1.153-1~deb11u1 || =6.1.158-1~deb11u1 || =6.1.159-1~deb11u1 || =6.1.162-1~deb11u1 || =6.1.164-1~deb11u1 || >=0 <6.1.170-1~deb11u1 | 6.1.170-1~deb11u1 |
