6.1-stable review patch. If anyone has any objections, please let me know.
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From: Sebastian Andrzej Siewior bigeasy@linutronix.de
[ Upstream commit 7645629f7dc88cd777f98970134bf1a54c8d77e3 ]
If __bpf_prog_enter_sleepable_recur() detects recursion then it returns 0 without undoing rcu_read_lock_trace(), migrate_disable() or decrementing the recursion counter. This is fine in the JIT case because the JIT code will jump in the 0 case to the end and invoke the matching exit trampoline (__bpf_prog_exit_sleepable_recur()).
This is not the case in kern_sys_bpf() which returns directly to the caller with an error code.
Add __bpf_prog_exit_sleepable_recur() as clean up in the recursion case.
Fixes: b1d18a7574d0d ("bpf: Extend sys_bpf commands for bpf_syscall programs.") Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Jiri Olsa jolsa@kernel.org Link: https://lore.kernel.org/bpf/20230830080405.251926-2-bigeasy@linutronix.de Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/syscall.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7afec961c5728..76484137233a3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5138,6 +5138,7 @@ int kern_sys_bpf(int cmd, union bpf_attr *attr, unsigned int size) run_ctx.saved_run_ctx = NULL; if (!__bpf_prog_enter_sleepable_recur(prog, &run_ctx)) { /* recursion detected */ + __bpf_prog_exit_sleepable_recur(prog, 0, &run_ctx); bpf_prog_put(prog); return -EBUSY; }