From cbb0a561e64b25001039f0ac82170536b2ef4893 Mon Sep 17 00:00:00 2001
From: Eugene Syromiatnikov <esyr@openssl.org>
Date: Thu, 14 Aug 2025 19:15:09 +0200
Subject: [PATCH] crypto/bio/bio_print.c: reset max to zero if empty precision
 string is provided
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Per [1]:

    a null digit string is treated as zero.

[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html

Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>

Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28177)
---
 crypto/bio/bio_print.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/crypto/bio/bio_print.c b/crypto/bio/bio_print.c
index f8031743ac1..3cb4d285574 100644
--- a/crypto/bio/bio_print.c
+++ b/crypto/bio/bio_print.c
@@ -182,8 +182,11 @@ _dopr(char **sbuffer,
                 max = va_arg(args, int);
                 ch = *format++;
                 state = DP_S_MOD;
-            } else
+            } else {
+                if (max < 0)
+                    max = 0;
                 state = DP_S_MOD;
+            }
             break;
         case DP_S_MOD:
             switch (ch) {
-- 
2.47.3