From: Arnd Bergmann arnd@arndb.de
commit e910c8e3aa02dc456e2f4c32cb479523c326b534 upstream.
Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") introduced a warning for the autofs_dev_ioctl structure:
In function 'check_name', inlined from 'validate_dev_ioctl' at fs/autofs/dev-ioctl.c:131:9, inlined from '_autofs_dev_ioctl' at fs/autofs/dev-ioctl.c:624:8: fs/autofs/dev-ioctl.c:33:14: error: 'strchr' reading 1 or more bytes from a region of size 0 [-Werror=stringop-overread] 33 | if (!strchr(name, '/')) | ^~~~~~~~~~~~~~~~~ In file included from include/linux/auto_dev-ioctl.h:10, from fs/autofs/autofs_i.h:10, from fs/autofs/dev-ioctl.c:14: include/uapi/linux/auto_dev-ioctl.h: In function '_autofs_dev_ioctl': include/uapi/linux/auto_dev-ioctl.h:112:14: note: source object 'path' of size 0 112 | char path[0]; | ^~~~
This is easily fixed by changing the gnu 0-length array into a c99 flexible array. Since this is a uapi structure, we have to be careful about possible regressions but this one should be fine as they are equivalent here. While it would break building with ancient gcc versions that predate c99, it helps building with --std=c99 and -Wpedantic builds in user space, as well as non-gnu compilers. This means we probably also want it fixed in stable kernels.
Cc: stable@vger.kernel.org Cc: Kees Cook keescook@chromium.org Cc: "Gustavo A. R. Silva" gustavoars@kernel.org Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20230523081944.581710-1-arnd@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/filesystems/autofs-mount-control.rst | 2 +- Documentation/filesystems/autofs.rst | 2 +- include/uapi/linux/auto_dev-ioctl.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-)
--- a/Documentation/filesystems/autofs-mount-control.rst +++ b/Documentation/filesystems/autofs-mount-control.rst @@ -196,7 +196,7 @@ information and return operation results struct args_ismountpoint ismountpoint; };
- char path[0]; + char path[]; };
The ioctlfd field is a mount point file descriptor of an autofs mount --- a/Documentation/filesystems/autofs.rst +++ b/Documentation/filesystems/autofs.rst @@ -467,7 +467,7 @@ Each ioctl is passed a pointer to an `au struct args_ismountpoint ismountpoint; };
- char path[0]; + char path[]; };
For the **OPEN_MOUNT** and **IS_MOUNTPOINT** commands, the target --- a/include/uapi/linux/auto_dev-ioctl.h +++ b/include/uapi/linux/auto_dev-ioctl.h @@ -109,7 +109,7 @@ struct autofs_dev_ioctl { struct args_ismountpoint ismountpoint; };
- char path[0]; + char path[]; };
static inline void init_autofs_dev_ioctl(struct autofs_dev_ioctl *in)