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From: Aurelien Jarno <aurelien@aurel32.net>
To: libc-stable@sourceware.org
Cc: Noah Goldstein <goldstein.w.n@gmail.com>,
	Siddhesh Poyarekar <siddhesh@sourceware.org>
Subject: [COMMITTED 2.34 1/2] stdlib: Remove attr_write from mbstows if dst is NULL [BZ: 29265]
Date: Tue, 16 Aug 2022 00:17:07 +0200	[thread overview]
Message-ID: <20220815221707.2475899-1-aurelien@aurel32.net> (raw)

From: Noah Goldstein <goldstein.w.n@gmail.com>

mbstows is defined if dst is NULL and is defined to special cased if
dst is NULL so the fortify objsize check if incorrect in that case.

Tested on x86-64 linux.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

(cherry picked from commit 464d189b9622932a75302290625de84931656ec0)
---
 stdlib/Makefile      |  3 +++
 stdlib/bits/stdlib.h | 16 +++++++++++-----
 stdlib/testmb.c      |  7 +++++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/stdlib/Makefile b/stdlib/Makefile
index a4ac30d1f6..e13f1ee33c 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -217,6 +217,9 @@ CFLAGS-tst-qsort.c += $(stack-align-test-flags)
 CFLAGS-tst-makecontext.c += -funwind-tables
 CFLAGS-tst-makecontext2.c += $(stack-align-test-flags)
 
+CFLAGS-testmb.c += -D_FORTIFY_SOURCE=2 -Wall -Werror
+
+
 # Run a test on the header files we use.
 tests-special += $(objpfx)isomac.out
 
diff --git a/stdlib/bits/stdlib.h b/stdlib/bits/stdlib.h
index ccacbdf76a..f0918d5d79 100644
--- a/stdlib/bits/stdlib.h
+++ b/stdlib/bits/stdlib.h
@@ -96,6 +96,11 @@ extern size_t __mbstowcs_chk (wchar_t *__restrict __dst,
 			      const char *__restrict __src,
 			      size_t __len, size_t __dstlen) __THROW
     __attr_access ((__write_only__, 1, 3)) __attr_access ((__read_only__, 2));
+extern size_t __REDIRECT_NTH (__mbstowcs_chk_nulldst,
+			      (wchar_t *__restrict __dst,
+			       const char *__restrict __src,
+			       size_t __len), mbstowcs_chk)
+    __attr_access ((__read_only__, 2));
 extern size_t __REDIRECT_NTH (__mbstowcs_alias,
 			      (wchar_t *__restrict __dst,
 			       const char *__restrict __src,
@@ -108,16 +113,17 @@ extern size_t __REDIRECT_NTH (__mbstowcs_chk_warn,
      __warnattr ("mbstowcs called with dst buffer smaller than len "
 		 "* sizeof (wchar_t)");
 
-__fortify_function size_t
+__always_inline __fortify_function size_t
 __NTH (mbstowcs (wchar_t *__restrict __dst, const char *__restrict __src,
 		 size_t __len))
 {
-  return __glibc_fortify_n (mbstowcs, __len, sizeof (wchar_t),
-			    __glibc_objsize (__dst),
-			    __dst, __src, __len);
+  if (__builtin_constant_p (__dst == NULL) && __dst == NULL)
+    return __mbstowcs_chk_nulldst (__dst, __src, __len);
+  else
+    return __glibc_fortify_n (mbstowcs, __len, sizeof (wchar_t),
+			      __glibc_objsize (__dst), __dst, __src, __len);
 }
 
-
 extern size_t __wcstombs_chk (char *__restrict __dst,
 			      const wchar_t *__restrict __src,
 			      size_t __len, size_t __dstlen) __THROW
diff --git a/stdlib/testmb.c b/stdlib/testmb.c
index 45dae7db61..6ac4dfd21d 100644
--- a/stdlib/testmb.c
+++ b/stdlib/testmb.c
@@ -16,6 +16,13 @@ main (int argc, char *argv[])
       lose = 1;
     }
 
+  i = mbstowcs (NULL, "bar", 4);
+  if (!(i == 3 && w[1] == 'a'))
+    {
+      puts ("mbstowcs FAILED2!");
+      lose = 1;
+    }
+
   mbstowcs (w, "blah", 5);
   i = wcstombs (c, w, 10);
   if (i != 4)
-- 
2.35.1


             reply	other threads:[~2022-08-15 22:17 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-15 22:17 Aurelien Jarno [this message]
2022-08-15 22:17 ` [COMMITTED 2.34 2/2] stdlib: Fixup mbstowcs NULL __dst handling. [BZ #29279] Aurelien Jarno

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