netdev - [PATCH 1/2] tools, bpf_asm: Hard error on out of range jumps.

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Message-Id: <af571eef0bc5d33180879c0c81a7d1b26431b915.1614134213.git.ian@zenhack.net>
Date:   Tue, 23 Feb 2021 21:15:31 -0500
From:   Ian Denhardt <ian@...hack.net>
To:     ast@...nel.org, daniel@...earbox.net, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH 1/2] tools, bpf_asm: Hard error on out of range jumps.

Per discussion at:

https://lore.kernel.org/bpf/c964892195a6b91d20a67691448567ef528ffa6d.camel@linux.ibm.com/T/#t

...this was originally introduced as a warning due to concerns about
breaking existing code, but a hard error probably makes more sense,
especially given that concerns about breakage were only speculation.
---
 tools/bpf/bpf_exp.y | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpf_exp.y b/tools/bpf/bpf_exp.y
index 8d48e896be50..8d03e5245da5 100644
--- a/tools/bpf/bpf_exp.y
+++ b/tools/bpf/bpf_exp.y
@@ -549,9 +549,11 @@ static uint8_t bpf_encode_jt_jf_offset(int off, int i)
 {
 	int delta = off - i - 1;
 
-	if (delta < 0 || delta > 255)
-		fprintf(stderr, "warning: insn #%d jumps to insn #%d, "
+	if (delta < 0 || delta > 255) {
+		fprintf(stderr, "error: insn #%d jumps to insn #%d, "
 				"which is out of range\n", i, off);
+		exit(1);
+	}
 	return (uint8_t) delta;
 }
 
-- 
2.30.1