6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20230830080405.251926-2-bigeasy@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/bpf/syscall.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a2aef900519c2..c925c270ed8b4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5307,6 +5307,7 @@ 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;
}
--
2.40.1
