[Buildroot] [PATCH 1/1] package/safeclib: fix build error with gcc 15.x

[Buildroot] [PATCH 1/1] package/safeclib: fix build error with gcc 15.x

[Bernd Kuhls]

This defconfig can be built without problems:

BR2_x86_64=y
BR2_GCC_VERSION_15_X=y
BR2_PACKAGE_SAFECLIB=y

However adding rocketlake as architecture variant

BR2_x86_64=y
BR2_x86_rocketlake=y
BR2_GCC_VERSION_15_X=y
BR2_PACKAGE_SAFECLIB=y

causes a build error:

str/vsnprintf_s.c: In function 'safec_ftoa.isra':
str/vsnprintf_s.c:523:24: error: writing 32 bytes into a region of size
 31 [-Werror=stringop-overflow=]
  523 |             buf[len++] = '0';

with gcc 15.x only, gcc =< 14.x is not affected, reason unknown.

This commit adds two upstream commits which fix the problem.

No autobuilder error was recorded.

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
---
 ...snprintf_s-Increase-Buffer-Size-by-1.patch | 47 +++++++++++++++++
 ...snprintf_s-Increase-Buffer-Size-by-1.patch | 50 +++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 package/safeclib/0001-vsnprintf_s-Increase-Buffer-Size-by-1.patch
 create mode 100644 package/safeclib/0002-vsnprintf_s-Increase-Buffer-Size-by-1.patch

diff --git a/package/safeclib/0001-vsnprintf_s-Increase-Buffer-Size-by-1.patch b/package/safeclib/0001-vsnprintf_s-Increase-Buffer-Size-by-1.patch
new file mode 100644
index 0000000000..f99f56f08c
--- /dev/null
+++ b/package/safeclib/0001-vsnprintf_s-Increase-Buffer-Size-by-1.patch
@@ -0,0 +1,47 @@
+From f59a0c8c1b5cf19cd0ed7f9bfb3a1e85f54113d0 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Wed, 13 Aug 2025 20:23:48 -0700
+Subject: [PATCH] vsnprintf_s: Increase Buffer Size by 1
+
+It is a buffer overflow warning that GCC 15.2 is catching.
+The issue is that it's trying to write to `buf[len++]` when len could
+potentially be 31, which would write to buf[31] in a buffer of size 32
+(valid indices 0-31), but the len++ post-increment means it could
+theoretically write beyond the buffer bounds.
+
+Fixes
+
+../../sources/safec-3.9.1/src/str/vsnprintf_s.c: In function 'safec_ftoa.isra':
+../../sources/safec-3.9.1/src/str/vsnprintf_s.c:523:24: error: writing 32 bytes into a region of size 31 [-Werror=stringop-overflow=]
+  523 |             buf[len++] = '0';
+      |             ~~~~~~~~~~~^~~~~
+../../sources/safec-3.9.1/src/str/vsnprintf_s.c:394:10: note: at offset [1, 32] into destination object 'buf' of size 32
+  394 |     char buf[PRINTF_FTOA_BUFFER_SIZE];
+      |          ^~~
+cc1: all warnings being treated as errors
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+
+Upstream: https://github.com/rurban/safeclib/commit/f59a0c8c1b5cf19cd0ed7f9bfb3a1e85f54113d0
+
+Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
+---
+ src/str/vsnprintf_s.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/str/vsnprintf_s.c b/src/str/vsnprintf_s.c
+index fa53ab42..0b62c3cb 100644
+--- a/src/str/vsnprintf_s.c
++++ b/src/str/vsnprintf_s.c
+@@ -391,7 +391,7 @@ static size_t safec_ftoa(out_fct_type out, const char *funcname, char *buffer,
+                          size_t idx, size_t maxlen, double value,
+                          unsigned int prec, unsigned int width,
+                          unsigned int flags) {
+-    char buf[PRINTF_FTOA_BUFFER_SIZE];
++    char buf[PRINTF_FTOA_BUFFER_SIZE + 1]; // Add extra byte for safety
+     size_t len = 0U, off = 0U;
+     double tmp;
+     double diff = 0.0;
+-- 
+2.47.3
+
diff --git a/package/safeclib/0002-vsnprintf_s-Increase-Buffer-Size-by-1.patch b/package/safeclib/0002-vsnprintf_s-Increase-Buffer-Size-by-1.patch
new file mode 100644
index 0000000000..4301426747
--- /dev/null
+++ b/package/safeclib/0002-vsnprintf_s-Increase-Buffer-Size-by-1.patch
@@ -0,0 +1,50 @@
+From 79e1445f4b3689526b46121b1218cab802b9ae88 Mon Sep 17 00:00:00 2001
+From: Bernd Kuhls <bernd@kuhls.net>
+Date: Sat, 10 Jan 2026 12:16:22 +0100
+Subject: [PATCH] vsnprintf_s: Increase Buffer Size by 1
+
+Another fix similar to https://github.com/rurban/safeclib/commit/f59a0c8c1b5cf19cd0ed7f9bfb3a1e85f54113d0
+
+In function 'safec_ntoa_format',
+    inlined from 'safec_ntoa_long' at str/vsnprintf_s.c:331:12:
+str/vsnprintf_s.c:256:24: error: writing 32 bytes into a region of size 0 [-Werror=stringop-overflow=]
+  256 |             buf[len++] = '0';
+      |             ~~~~~~~~~~~^~~~~
+str/vsnprintf_s.c: In function 'safec_ntoa_long':
+str/vsnprintf_s.c:312:10: note: at offset 32 into destination object 'buf' of size 32
+  312 |     char buf[PRINTF_NTOA_BUFFER_SIZE];
+      |          ^~~
+In function 'safec_ntoa_format',
+    inlined from 'safec_ntoa_long' at str/vsnprintf_s.c:331:12:
+str/vsnprintf_s.c:260:24: error: writing 32 bytes into a region of size 0 [-Werror=stringop-overflow=]
+  260 |             buf[len++] = '0';
+      |             ~~~~~~~~~~~^~~~~
+str/vsnprintf_s.c: In function 'safec_ntoa_long':
+str/vsnprintf_s.c:312:10: note: at offset 32 into destination object 'buf' of size 32
+  312 |     char buf[PRINTF_NTOA_BUFFER_SIZE];
+      |          ^~~
+cc1: all warnings being treated as errors
+
+Upstream: https://github.com/rurban/safeclib/commit/79e1445f4b3689526b46121b1218cab802b9ae88
+
+Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
+---
+ src/str/vsnprintf_s.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/str/vsnprintf_s.c b/src/str/vsnprintf_s.c
+index 0b62c3cb..cf8e866e 100644
+--- a/src/str/vsnprintf_s.c
++++ b/src/str/vsnprintf_s.c
+@@ -309,7 +309,7 @@ static size_t safec_ntoa_long(out_fct_type out, const char *funcname,
+                               unsigned long value, bool negative,
+                               unsigned long base, unsigned int prec,
+                               unsigned int width, unsigned int flags) {
+-    char buf[PRINTF_NTOA_BUFFER_SIZE];
++    char buf[PRINTF_NTOA_BUFFER_SIZE + 1];
+     size_t len = 0U;
+ 
+     // no hash for 0 values
+-- 
+2.47.3
+
-- 
2.47.3

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Re: [Buildroot] [PATCH 1/1] package/safeclib: fix build error with gcc 15.x

[Peter Korsgaard]

>>>>> "Bernd" == Bernd Kuhls <bernd@kuhls.net> writes:

 > This defconfig can be built without problems:
 > BR2_x86_64=y
 > BR2_GCC_VERSION_15_X=y
 > BR2_PACKAGE_SAFECLIB=y

 > However adding rocketlake as architecture variant

 > BR2_x86_64=y
 > BR2_x86_rocketlake=y
 > BR2_GCC_VERSION_15_X=y
 > BR2_PACKAGE_SAFECLIB=y

 > causes a build error:

 > str/vsnprintf_s.c: In function 'safec_ftoa.isra':
 > str/vsnprintf_s.c:523:24: error: writing 32 bytes into a region of size
 >  31 [-Werror=stringop-overflow=]
 >   523 |             buf[len++] = '0';

 > with gcc 15.x only, gcc =< 14.x is not affected, reason unknown.

 > This commit adds two upstream commits which fix the problem.

 > No autobuilder error was recorded.

 > Signed-off-by: Bernd Kuhls <bernd@kuhls.net>

Committed, thanks.

-- 
Bye, Peter Korsgaard
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