From 01be844fcf75364d429b1dd0ef657e48ba8ef3de Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast@kernel.org>
Date: Mon, 3 Dec 2018 22:46:04 -0800
Subject: bpf: check pending signals while verifying programs

[ Upstream commit c3494801cd1785e2c25f1a5735fa19ddcf9665da ]

Malicious user space may try to force the verifier to use as much cpu
time and memory as possible. Hence check for pending signals
while verifying the program.
Note that suspend of sys_bpf(PROG_LOAD) syscall will lead to EAGAIN,
since the kernel has to release the resources used for program verification.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
---
 kernel/bpf/verifier.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'kernel')

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1438b7396cb4..335c00209f74 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2919,6 +2919,9 @@ static int do_check(struct bpf_verifier_env *env)
 			goto process_bpf_exit;
 		}
 
+		if (signal_pending(current))
+			return -EAGAIN;
+
 		if (need_resched())
 			cond_resched();
 
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