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From: Siddhesh Poyarekar <siddhesh@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] cdefs: Drop access attribute for _FORTIFY_SOURCE=3 (BZ #31383) Date: Wed, 28 Feb 2024 13:35:48 +0000 (GMT) [thread overview] Message-ID: <20240228133548.7DF173858C52@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=bf9688e623262c5fa9f91e4de0e84db45025076f commit bf9688e623262c5fa9f91e4de0e84db45025076f Author: Siddhesh Poyarekar <siddhesh@sourceware.org> Date: Thu Feb 15 07:40:56 2024 -0500 cdefs: Drop access attribute for _FORTIFY_SOURCE=3 (BZ #31383) When passed a pointer to a zero-sized struct, the access attribute without the third argument misleads -Wstringop-overflow diagnostics to think that a function is writing 1 byte into the zero-sized structs. The attribute doesn't add that much value in this context, so drop it completely for _FORTIFY_SOURCE=3. Resolves: BZ #31383 Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Diff: --- io/Makefile | 2 ++ io/tst-read-zero.c | 39 +++++++++++++++++++++++++++++++++++++++ misc/sys/cdefs.h | 6 +++--- 3 files changed, 44 insertions(+), 3 deletions(-) diff --git a/io/Makefile b/io/Makefile index 54d950d51f..19932d50f7 100644 --- a/io/Makefile +++ b/io/Makefile @@ -215,6 +215,7 @@ tests := \ tst-openat \ tst-posix_fallocate \ tst-posix_fallocate64 \ + tst-read-zero \ tst-readlinkat \ tst-renameat \ tst-stat \ @@ -290,6 +291,7 @@ CFLAGS-read.c += -fexceptions -fasynchronous-unwind-tables $(config-cflags-wno-i CFLAGS-write.c += -fexceptions -fasynchronous-unwind-tables $(config-cflags-wno-ignored-attributes) CFLAGS-close.c += -fexceptions -fasynchronous-unwind-tables CFLAGS-lseek64.c += $(config-cflags-wno-ignored-attributes) +CFLAGS-tst-read-zero.c += $(no-fortify-source),-D_FORTIFY_SOURCE=$(supported-fortify) CFLAGS-test-stat.c += -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE CFLAGS-test-lfs.c += -D_LARGEFILE64_SOURCE diff --git a/io/tst-read-zero.c b/io/tst-read-zero.c new file mode 100644 index 0000000000..8d1d30a543 --- /dev/null +++ b/io/tst-read-zero.c @@ -0,0 +1,39 @@ +/* read smoke test for 0-sized structures. + Copyright The GNU Toolchain Authors. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Zero-sized structures should not result in any overflow warnings or + errors when fortification is enabled. */ +#include <fcntl.h> +#include <stdio.h> +#include <unistd.h> +#include <support/check.h> + +int +do_test (void) +{ + struct test_st {} test_info[16]; + int fd = open ("/dev/zero", O_RDONLY, 0); + + if (fd == -1) + FAIL_UNSUPPORTED ("Unable to open /dev/zero: %m"); + + TEST_VERIFY_EXIT (read (fd, test_info, sizeof(test_info)) == 0); + return 0; +} + +#include <support/test-driver.c> diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h index 6b03417453..2e8279a2c7 100644 --- a/misc/sys/cdefs.h +++ b/misc/sys/cdefs.h @@ -837,10 +837,10 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf # define __attr_access(x) __attribute__ ((__access__ x)) /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may use the access attribute to get object sizes from function definition - arguments, so we can't use them on functions we fortify. Drop the object - size hints for such functions. */ + arguments, so we can't use them on functions we fortify. Drop the access + attribute for such functions. */ # if __USE_FORTIFY_LEVEL == 3 -# define __fortified_attr_access(a, o, s) __attribute__ ((__access__ (a, o))) +# define __fortified_attr_access(a, o, s) # else # define __fortified_attr_access(a, o, s) __attr_access ((a, o, s)) # endif
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