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From: Fedor Tokarev <ftokarev@gmail.com>
To: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, ftokarev@gmail.com
Subject: [PATCH] bpf: btf: Fix vsnprintf return value check
Date: Mon, 11 Jul 2022 23:13:17 +0200	[thread overview]
Message-ID: <20220711211317.GA1143610@laptop> (raw)

vsnprintf returns the number of characters which would have been written if
enough space had been available, excluding the terminating null byte. Thus,
the return value of 'len_left' means that the last character has been
dropped.

Signed-off-by: Fedor Tokarev <ftokarev@gmail.com>
---
 kernel/bpf/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index eb12d4f705cc..a9c1c98017d4 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6519,7 +6519,7 @@ static void btf_snprintf_show(struct btf_show *show, const char *fmt,
 	if (len < 0) {
 		ssnprintf->len_left = 0;
 		ssnprintf->len = len;
-	} else if (len > ssnprintf->len_left) {
+	} else if (len >= ssnprintf->len_left) {
 		/* no space, drive on to get length we would have written */
 		ssnprintf->len_left = 0;
 		ssnprintf->len += len;
-- 
2.25.1


             reply	other threads:[~2022-07-11 21:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-11 21:13 Fedor Tokarev [this message]
2022-07-11 21:42 ` [PATCH] bpf: btf: Fix vsnprintf return value check Jiri Olsa
2022-07-13 18:40   ` Andrii Nakryiko
2022-07-14 10:06     ` Alan Maguire
2022-07-15  7:07       ` Fedor Tokarev
2022-07-25  7:41         ` Alan Maguire

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