[openssh-commits] [openssh] 06/87: fix BROKEN_SNPRINTF replacement for max-width ints

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djm pushed a commit to branch master
in repository openssh.

commit 74551008cc2f1ec5f34a7c5b5b1aa62df52cecdd
Author: Damien Miller <djm at mindrot.org>
AuthorDate: Fri Oct 30 18:56:22 2026 +1100

    fix BROKEN_SNPRINTF replacement for max-width ints
    
    Previous implementation incorrectly truncating integers that needed more
    than 19 decimal places.
    
    Anthropic ANT-2026-LRFWCWHP
---
 openbsd-compat/bsd-snprintf.c         |  5 ++---
 openbsd-compat/regress/snprintftest.c | 10 +++++++++-
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/openbsd-compat/bsd-snprintf.c b/openbsd-compat/bsd-snprintf.c
index 56160eeca..2ee173fd6 100644
--- a/openbsd-compat/bsd-snprintf.c
+++ b/openbsd-compat/bsd-snprintf.c
@@ -544,7 +544,7 @@ fmtint(char *buffer, size_t *currlen, size_t maxlen,
 {
 	int signvalue = 0;
 	unsigned LLONG uvalue;
-	char convert[20];
+	char convert[sizeof(uvalue) * CHAR_BIT / 3 + 2]; /* octal digits + NUL */
 	int place = 0;
 	int spadlen = 0; /* amount to space pad */
 	int zpadlen = 0; /* amount to zero pad */
@@ -574,8 +574,7 @@ fmtint(char *buffer, size_t *currlen, size_t maxlen,
 			(caps? "0123456789ABCDEF":"0123456789abcdef")
 			[uvalue % (unsigned)base  ];
 		uvalue = (uvalue / (unsigned)base );
-	} while(uvalue && (place < 20));
-	if (place == 20) place--;
+	} while(uvalue && (place < (int)sizeof(convert) - 1));
 	convert[place] = 0;
 
 	zpadlen = max - place;
diff --git a/openbsd-compat/regress/snprintftest.c b/openbsd-compat/regress/snprintftest.c
index 23b7dfac8..8d844289d 100644
--- a/openbsd-compat/regress/snprintftest.c
+++ b/openbsd-compat/regress/snprintftest.c
@@ -48,7 +48,7 @@ int x_snprintf(char *str, size_t count, const char *fmt, ...)
 int
 main(void)
 {
-	char b[5];
+	char b[5], n[32];
 	char *src = NULL;
 	int ret;
 
@@ -73,6 +73,14 @@ main(void)
 	if (x_snprintf(b, 1, "%s %d", "hello", 12345) != 11)
 		fail("vsnprintf does not return required length");
 
+	/* check that the largest 64-bit values are printed in full */
+	ret = snprintf(n, sizeof(n), "%llu", 0xffffffffffffffffULL);
+	if (ret != 20 || strcmp(n, "18446744073709551615") != 0)
+		fail("snprintf truncates 20-digit unsigned values");
+	ret = snprintf(n, sizeof(n), "%llo", 0xffffffffffffffffULL);
+	if (ret != 22 || strcmp(n, "1777777777777777777777") != 0)
+		fail("snprintf truncates 22-digit octal values");
+
 	free(src);
 	return failed;
 }

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