From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Kui-Feng Lee <kuifeng@fb.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 1/2] bpf: Invoke __bpf_prog_exit_sleepable_recur() on recursion in kern_sys_bpf().
Date: Wed, 30 Aug 2023 10:04:04 +0200 [thread overview]
Message-ID: <20230830080405.251926-2-bigeasy@linutronix.de> (raw)
In-Reply-To: <20230830080405.251926-1-bigeasy@linutronix.de>
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>
---
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
next prev parent reply other threads:[~2023-08-30 8:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 8:04 [PATCH 0/2] bpf: Recursion detection related fixes Sebastian Andrzej Siewior
2023-08-30 8:04 ` Sebastian Andrzej Siewior [this message]
2023-09-01 14:02 ` [PATCH 1/2] bpf: Invoke __bpf_prog_exit_sleepable_recur() on recursion in kern_sys_bpf() Jiri Olsa
2023-08-30 8:04 ` [PATCH 2/2] bpf: Assign bpf_tramp_run_ctx::saved_run_ctx before recursion check Sebastian Andrzej Siewior
2023-09-01 14:13 ` Jiri Olsa
2023-09-01 14:19 ` Sebastian Andrzej Siewior
2023-09-06 8:52 ` Daniel Borkmann
2023-09-07 10:12 ` Sebastian Andrzej Siewior
2023-09-06 9:00 ` [PATCH 0/2] bpf: Recursion detection related fixes patchwork-bot+netdevbpf
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