From: Jann Horn jannh@google.com

stable inclusion from stable-v6.6.67 commit f9f85df30118f3f4112761e6682fc60ebcce23e5 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEAKR CVE: CVE-2024-56675

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit ef1b808e3b7c98612feceedf985c2fbbeb28f956 upstream.

Uprobes always use bpf_prog_run_array_uprobe() under tasks-trace-RCU protection. But it is possible to attach a non-sleepable BPF program to a uprobe, and non-sleepable BPF programs are freed via normal RCU (see __bpf_prog_put_noref()). This leads to UAF of the bpf_prog because a normal RCU grace period does not imply a tasks-trace-RCU grace period.

Fix it by explicitly waiting for a tasks-trace-RCU grace period after removing the attachment of a bpf_prog to a perf_event.

Fixes: 8c7dcb84e3b7 ("bpf: implement sleepable uprobes by chaining gps") Suggested-by: Andrii Nakryiko andrii@kernel.org Suggested-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Jann Horn jannh@google.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20241210-bpf-fix-actual-uprobe-uaf-v1-1-19439849... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Pu Lehui pulehui@huawei.com --- kernel/trace/bpf_trace.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 93e06d370395..b084fe1dbe12 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2224,6 +2224,13 @@ void perf_event_detach_bpf_prog(struct perf_event *event) bpf_prog_array_free_sleepable(old_array); }

+ /* + * It could be that the bpf_prog is not sleepable (and will be freed + * via normal RCU), but is called from a point that supports sleepable + * programs and uses tasks-trace-RCU. + */ + synchronize_rcu_tasks_trace(); + bpf_prog_put(event->prog); event->prog = NULL;