4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann <daniel@xxxxxxxxxxxxx> [ Upstream commit ceb56070359b7329b5678b5d95a376fcb24767be ] Commit dead9f29ddcc ("perf: Fix race in BPF program unregister") moved destruction of BPF program from free_event_rcu() callback to __free_event(), which is problematic if used with tail calls: if prog A is attached as trace event directly, but at the same time present in a tail call map used by another trace event program elsewhere, then we need to delay destruction via RCU grace period since it can still be in use by the program doing the tail call (the prog first needs to be dropped from the tail call map, then trace event with prog A attached destroyed, so we get immediate destruction). Fixes: dead9f29ddcc ("perf: Fix race in BPF program unregister") Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Jann Horn <jann@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/bpf.h | 4 ++++ kernel/events/core.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -229,6 +229,10 @@ static inline struct bpf_prog *bpf_prog_ static inline void bpf_prog_put(struct bpf_prog *prog) { } + +static inline void bpf_prog_put_rcu(struct bpf_prog *prog) +{ +} #endif /* CONFIG_BPF_SYSCALL */ /* verifier prototypes for helper functions called from eBPF programs */ --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7143,7 +7143,7 @@ static void perf_event_free_bpf_prog(str prog = event->tp_event->prog; if (prog) { event->tp_event->prog = NULL; - bpf_prog_put(prog); + bpf_prog_put_rcu(prog); } } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html