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[v3,16/17] configure: Prohibit alloca() by using -Walloca CPPFLAG

Message ID 20210507144315.1994337-17-philmd@redhat.com
State New
Headers show
Series misc: Replace alloca() by g_malloc() | expand

Commit Message

Philippe Mathieu-Daudé May 7, 2021, 2:43 p.m. UTC
Now that we removed all alloca() calls in the repository, add the
-Walloca CPPFLAG to trigger a build failure if such stack allocation
is used.

Rationale: The ALLOCA(3) man-page mentions its "use is discouraged".

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
As there is an alloca() call in libslirp, this patch is pending
on the following libslirp patch to be merged:
https://lists.freedesktop.org/archives/slirp/2021-May/000150.html
(and the submodule updated).
---
 configure | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Philippe Mathieu-Daudé May 7, 2021, 5:14 p.m. UTC | #1
On 5/7/21 4:43 PM, Philippe Mathieu-Daudé wrote:
> Now that we removed all alloca() calls in the repository, add the
> -Walloca CPPFLAG to trigger a build failure if such stack allocation
> is used.
> 
> Rationale: The ALLOCA(3) man-page mentions its "use is discouraged".
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> As there is an alloca() call in libslirp, this patch is pending
> on the following libslirp patch to be merged:
> https://lists.freedesktop.org/archives/slirp/2021-May/000150.html
> (and the submodule updated).
> ---
>  configure | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 4f374b48890..67cb6d5421c 100755
> --- a/configure
> +++ b/configure
> @@ -552,7 +552,7 @@ ARFLAGS="${ARFLAGS-rv}"
>  # provides these semantics.)
>  QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv $QEMU_CFLAGS"
>  QEMU_CFLAGS="-Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
> -QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
> +QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls -Walloca $QEMU_CFLAGS"
>  QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"

Sigh I forgot one Clang version (7.0.1) doesn't recognize this warning.

I'll replace this patch by:

-- >8 --
diff --git a/configure b/configure
index 4f374b48890..4330245fa1f 100755
--- a/configure
+++ b/configure
@@ -2083,2 +2083,3 @@ add_to warn_flags -Wexpansion-to-defined
 add_to warn_flags -Wimplicit-fallthrough=2
+add_to warn_flags -Walloca

---

Regards,

Phil.
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Patch

diff --git a/configure b/configure
index 4f374b48890..67cb6d5421c 100755
--- a/configure
+++ b/configure
@@ -552,7 +552,7 @@  ARFLAGS="${ARFLAGS-rv}"
 # provides these semantics.)
 QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
-QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
+QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls -Walloca $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
 
 # Flags that are needed during configure but later taken care of by Meson