debug: make __read_chk a cancellation point (bug 29274)
Checks
Commit Message
The __read_chk function, as the implementation behind the fortified read
function, must be a cancellation point, thus it cannot use INLINE_SYSCALL.
---
debug/Makefile | 7 ++++++
debug/read_chk.c | 10 --------
debug/tst-read-chk-cancel.c | 50 +++++++++++++++++++++++++++++++++++++
3 files changed, 57 insertions(+), 10 deletions(-)
create mode 100644 debug/tst-read-chk-cancel.c
Comments
On 22/06/2022 20:14, Andreas Schwab via Libc-alpha wrote:
> The __read_chk function, as the implementation behind the fortified read
> function, must be a cancellation point, thus it cannot use INLINE_SYSCALL.
> ---
> debug/Makefile | 7 ++++++
> debug/read_chk.c | 10 --------
> debug/tst-read-chk-cancel.c | 50 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 57 insertions(+), 10 deletions(-)
> create mode 100644 debug/tst-read-chk-cancel.c
LGTM.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
>
> diff --git a/debug/Makefile b/debug/Makefile
> index 96029f32ee..456b349c4d 100644
> --- a/debug/Makefile
> +++ b/debug/Makefile
> @@ -110,6 +110,7 @@ CPPFLAGS-tst-longjmp_chk2.c += -D_FORTIFY_SOURCE=1
> CFLAGS-tst-longjmp_chk3.c += -fexceptions -fasynchronous-unwind-tables
> CPPFLAGS-tst-longjmp_chk3.c += -D_FORTIFY_SOURCE=1
> CPPFLAGS-tst-realpath-chk.c += -D_FORTIFY_SOURCE=2
> +CPPFLAGS-tst-read-chk-cancel.c += -D_FORTIFY_SOURCE=2
>
> # _FORTIFY_SOURCE tests.
> # Auto-generate tests for _FORTIFY_SOURCE for different levels, compilers and
> @@ -204,6 +205,10 @@ ifeq ($(have-ssp),yes)
> tests += tst-ssp-1
> endif
>
> +ifeq ($(have-thread-library), yes)
> +tests += tst-read-chk-cancel
> +endif
> +
> ifeq (,$(CXX))
> tests-unsupported = $(tests-cc-chk)
> endif
> @@ -242,3 +247,5 @@ $(objpfx)xtrace: xtrace.sh
> -e 's|@BINDIR@|$(bindir)|' -e 's|@PKGVERSION@|$(PKGVERSION)|' \
> -e 's|@REPORT_BUGS_TO@|$(REPORT_BUGS_TO)|' $^ > $@.new \
> && rm -f $@ && mv $@.new $@ && chmod +x $@
> +
> +$(objpfx)tst-read-chk-cancel: $(shared-thread-library)
> diff --git a/debug/read_chk.c b/debug/read_chk.c
> index 0cd58db8cb..274b4f93e9 100644
> --- a/debug/read_chk.c
> +++ b/debug/read_chk.c
> @@ -16,12 +16,6 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <unistd.h>
> -#include <sys/param.h>
> -#ifdef HAVE_INLINED_SYSCALLS
> -# include <errno.h>
> -# include <sysdep.h>
> -#endif
> -
>
> ssize_t
> __read_chk (int fd, void *buf, size_t nbytes, size_t buflen)
> @@ -29,9 +23,5 @@ __read_chk (int fd, void *buf, size_t nbytes, size_t buflen)
> if (nbytes > buflen)
> __chk_fail ();
>
> -#ifdef HAVE_INLINED_SYSCALLS
> - return INLINE_SYSCALL (read, 3, fd, buf, nbytes);
> -#else
> return __read (fd, buf, nbytes);
> -#endif
> }
> diff --git a/debug/tst-read-chk-cancel.c b/debug/tst-read-chk-cancel.c
> new file mode 100644
> index 0000000000..7e06afb596
> --- /dev/null
> +++ b/debug/tst-read-chk-cancel.c
> @@ -0,0 +1,50 @@
> +/* Test that __read_chk is a cancellation point (BZ #29274)
> + Copyright (C) 2022 Free Software Foundation, Inc.
> + 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/>. */
> +
> +#include <stdint.h>
> +#include <support/xunistd.h>
> +#include <support/xthread.h>
> +
> +static int pipe_fds[2];
> +static pthread_barrier_t barrier;
> +
> +static void *
> +read_thread (void *n)
> +{
> + xpthread_barrier_wait (&barrier);
> + char c;
> + /* This call should be forwarded to __read_chk because the buffer size
> + is known, but the read length is non-constant. */
> + if (read (pipe_fds[0], &c, (uintptr_t) n) != 1)
> + return (void *) -1L;
> + return 0;
> +}
> +
> +static int
> +do_test (void)
> +{
> + xpthread_barrier_init (&barrier, 0, 2);
> + xpipe (pipe_fds);
> + pthread_t thr = xpthread_create (0, read_thread, (void *) 1L);
> + xpthread_barrier_wait (&barrier);
> + xpthread_cancel (thr);
> + xpthread_join (thr);
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> On 22 Jun 2022, at 11:44, Andreas Schwab via Libc-alpha <libc-alpha@sourceware.org> wrote:
>
> The __read_chk function, as the implementation behind the fortified read
> function, must be a cancellation point, thus it cannot use INLINE_SYSCALL.
> ---
> debug/Makefile | 7 ++++++
> debug/read_chk.c | 10 --------
> debug/tst-read-chk-cancel.c | 50 +++++++++++++++++++++++++++++++++++++
Maybe add a tst-cancel4-chk that builds with _FORTIFY_SOURCE=2 so we can tests
more cancellation entrypoints?
@@ -110,6 +110,7 @@ CPPFLAGS-tst-longjmp_chk2.c += -D_FORTIFY_SOURCE=1
CFLAGS-tst-longjmp_chk3.c += -fexceptions -fasynchronous-unwind-tables
CPPFLAGS-tst-longjmp_chk3.c += -D_FORTIFY_SOURCE=1
CPPFLAGS-tst-realpath-chk.c += -D_FORTIFY_SOURCE=2
+CPPFLAGS-tst-read-chk-cancel.c += -D_FORTIFY_SOURCE=2
# _FORTIFY_SOURCE tests.
# Auto-generate tests for _FORTIFY_SOURCE for different levels, compilers and
@@ -204,6 +205,10 @@ ifeq ($(have-ssp),yes)
tests += tst-ssp-1
endif
+ifeq ($(have-thread-library), yes)
+tests += tst-read-chk-cancel
+endif
+
ifeq (,$(CXX))
tests-unsupported = $(tests-cc-chk)
endif
@@ -242,3 +247,5 @@ $(objpfx)xtrace: xtrace.sh
-e 's|@BINDIR@|$(bindir)|' -e 's|@PKGVERSION@|$(PKGVERSION)|' \
-e 's|@REPORT_BUGS_TO@|$(REPORT_BUGS_TO)|' $^ > $@.new \
&& rm -f $@ && mv $@.new $@ && chmod +x $@
+
+$(objpfx)tst-read-chk-cancel: $(shared-thread-library)
@@ -16,12 +16,6 @@
<https://www.gnu.org/licenses/>. */
#include <unistd.h>
-#include <sys/param.h>
-#ifdef HAVE_INLINED_SYSCALLS
-# include <errno.h>
-# include <sysdep.h>
-#endif
-
ssize_t
__read_chk (int fd, void *buf, size_t nbytes, size_t buflen)
@@ -29,9 +23,5 @@ __read_chk (int fd, void *buf, size_t nbytes, size_t buflen)
if (nbytes > buflen)
__chk_fail ();
-#ifdef HAVE_INLINED_SYSCALLS
- return INLINE_SYSCALL (read, 3, fd, buf, nbytes);
-#else
return __read (fd, buf, nbytes);
-#endif
}
new file mode 100644
@@ -0,0 +1,50 @@
+/* Test that __read_chk is a cancellation point (BZ #29274)
+ Copyright (C) 2022 Free Software Foundation, Inc.
+ 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/>. */
+
+#include <stdint.h>
+#include <support/xunistd.h>
+#include <support/xthread.h>
+
+static int pipe_fds[2];
+static pthread_barrier_t barrier;
+
+static void *
+read_thread (void *n)
+{
+ xpthread_barrier_wait (&barrier);
+ char c;
+ /* This call should be forwarded to __read_chk because the buffer size
+ is known, but the read length is non-constant. */
+ if (read (pipe_fds[0], &c, (uintptr_t) n) != 1)
+ return (void *) -1L;
+ return 0;
+}
+
+static int
+do_test (void)
+{
+ xpthread_barrier_init (&barrier, 0, 2);
+ xpipe (pipe_fds);
+ pthread_t thr = xpthread_create (0, read_thread, (void *) 1L);
+ xpthread_barrier_wait (&barrier);
+ xpthread_cancel (thr);
+ xpthread_join (thr);
+ return 0;
+}
+
+#include <support/test-driver.c>