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From:   Aditya Pakki <pakki001@umn.edu>
To:     pakki001@umn.edu
Cc:     kjlu@umn.edu, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] bpf: Replace BUG_ON when fp_old is NULL
Date:   Sun, 15 Dec 2019 09:44:32 -0600
Message-Id: <20191215154432.22399-1-pakki001@umn.edu>
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Sender: linux-kernel-owner@vger.kernel.org
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If fp_old is NULL in bpf_prog_realloc, the program does an assertion
and crashes. However, we can continue execution by returning NULL to
the upper callers. The patch fixes this issue.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
---
 kernel/bpf/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 49e32acad7d8..4b46654fb26b 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -222,7 +222,8 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 	u32 pages, delta;
 	int ret;
 
-	BUG_ON(fp_old == NULL);
+	if (!fp_old)
+		return NULL;
 
 	size = round_up(size, PAGE_SIZE);
 	pages = size / PAGE_SIZE;
-- 
2.20.1