linux-kernel - [PATCH v2] bpf: Remove unnecessary assertion on fp

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Date:   Thu, 19 Dec 2019 11:57:35 -0600
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] bpf: Remove unnecessary assertion on fp_old

The two callers of bpf_prog_realloc - bpf_patch_insn_single and
bpf_migrate_filter dereference the struct fp_old, before passing
it to the function. Thus assertion to check fp_old is unnecessary
and can be removed.

Signed-off-by: Aditya Pakki <pakki001@....edu>
---
v1: Remove the check on fp_old altogether, as suggested by
Daniel Borkmann and Alexei Starovoitov.
---
 kernel/bpf/core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 49e32acad7d8..ca010b783687 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -222,8 +222,6 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 	u32 pages, delta;
 	int ret;
 
-	BUG_ON(fp_old == NULL);
-
 	size = round_up(size, PAGE_SIZE);
 	pages = size / PAGE_SIZE;
 	if (pages <= fp_old->pages)
-- 
2.20.1