From e59bdf63cbe16b018f8b9b38f1daf9ece2329ab8 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri, 10 Jan 2025 14:06:06 -0300
Subject: [PATCH] stdio-common: Suppress Clang warnings on scanf13.c with
fortify enable
clang-19 shows:
scanf13.c:28:40: error: 'sscanf' may overflow; destination buffer in argument 4 has size 8, but the corresponding specifier may require size 11 [-Werror,-Wfortify-source]
28 | "A%ms%10ms%4m[bcd]%4mcB", &sp1, &sp2, &sp3, &sp4) != 4)
| ^
scanf13.c:94:34: error: 'sscanf' may overflow; destination buffer in argument 3 has size 8, but the corresponding specifier may require size 2049 [-Werror,-Wfortify-source]
94 | if (sscanf (buf, "%2048ms%mc", &sp3, &sp4) != 2)
| ^
scanf13.c:110:61: error: 'sscanf' may overflow; destination buffer in argument 4 has size 8, but the corresponding specifier may require size 1501 [-Werror,-Wfortify-source]
110 | if (sscanf (buf, "%4mc%1500m[dr/]%548m[abc/d]%3mc", &sp1, &sp2, &sp3, &sp4)
| ^
scanf13.c:110:67: error: 'sscanf' may overflow; destination buffer in argument 5 has size 8, but the corresponding specifier may require size 549 [-Werror,-Wfortify-source]
110 | if (sscanf (buf, "%4mc%1500m[dr/]%548m[abc/d]%3mc", &sp1, &sp2, &sp3, &sp4)
clang does have some support to handle 'm' prefix for -Wformat; but it
lacks support for -Wfortify to understand that it is up to libc to
allocate the memory, and uses the pointer size instead to calculate
validity.
---
stdio-common/scanf13.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/stdio-common/scanf13.c b/stdio-common/scanf13.c
index 65b1429720..131abb33de 100644
--- a/stdio-common/scanf13.c
+++ b/stdio-common/scanf13.c
@@ -24,6 +24,7 @@ main (void)
DIAG_PUSH_NEEDS_COMMENT_CLANG;
DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
+ DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wfortify-source");
if (sscanf ("A \xc3\x84-\t\t\xc3\x84-abcdefbcd\t\xc3\x84-B",
"A%ms%10ms%4m[bcd]%4mcB", &sp1, &sp2, &sp3, &sp4) != 4)
FAIL ();
@@ -91,6 +92,8 @@ main (void)
FAIL ();
free (sp2);
}
+ DIAG_PUSH_NEEDS_COMMENT_CLANG;
+ DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wfortify-source");
if (sscanf (buf, "%2048ms%mc", &sp3, &sp4) != 2)
FAIL ();
else
@@ -131,6 +134,7 @@ main (void)
FAIL ();
free (sp4);
}
+ DIAG_POP_NEEDS_COMMENT_CLANG;
if (sscanf (buf, "%mS%mC", &lsp1, &lsp2) != 2)
FAIL ();
else
@@ -150,6 +154,7 @@ main (void)
DIAG_PUSH_NEEDS_COMMENT_CLANG;
DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
+ DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wfortify-source");
if (sscanf (buf, "%2048mls%mlc", &lsp3, &lsp4) != 2)
FAIL ();
else