| Message ID | 20230105033743.never.628-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io_uring: Replace 0-length array with flexible array | expand |
On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote: > Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's > "bufs" with a flexible array member. (How is the size of this array > verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: > > In function 'io_ring_buffer_select', > inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: > io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] > 141 | buf = &br->bufs[head]; > | ^~~~~~~~~~~~~~~ > In file included from include/linux/io_uring.h:7, > from io_uring/kbuf.c:10: > include/uapi/linux/io_uring.h: In function 'io_buffer_select': > include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' > 628 | struct io_uring_buf bufs[0]; > | ^~~~ > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Pavel Begunkov <asml.silence@gmail.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: stable@vger.kernel.org > Cc: io-uring@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > include/uapi/linux/io_uring.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 2780bce62faf..9d8861899cde 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -625,7 +625,7 @@ struct io_uring_buf_ring { > __u16 resv3; > __u16 tail; > }; > - struct io_uring_buf bufs[0]; > + struct io_uring_buf bufs[]; > }; > }; Oops, please ignore. My test build misfired... > > -- > 2.34.1 >
Hi Kees,
I love your patch! Yet something to improve:
[auto build test ERROR on kees/for-next/pstore]
[also build test ERROR on kees/for-next/kspp linus/master v6.2-rc2 next-20230105]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Kees-Cook/io_uring-Replace-0-length-array-with-flexible-array/20230105-114008
base: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/pstore
patch link: https://lore.kernel.org/r/20230105033743.never.628-kees%40kernel.org
patch subject: [PATCH] io_uring: Replace 0-length array with flexible array
config: arc-defconfig
compiler: arc-elf-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/6239ffe2f8611e707b90e0c902bfa1f0dbe578bb
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Kees-Cook/io_uring-Replace-0-length-array-with-flexible-array/20230105-114008
git checkout 6239ffe2f8611e707b90e0c902bfa1f0dbe578bb
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
In file included from include/linux/io_uring.h:7,
from kernel/fork.c:97:
>> include/uapi/linux/io_uring.h:628:41: error: flexible array member in union
628 | struct io_uring_buf bufs[];
| ^~~~
kernel/fork.c:162:13: warning: no previous prototype for 'arch_release_task_struct' [-Wmissing-prototypes]
162 | void __weak arch_release_task_struct(struct task_struct *tsk)
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/fork.c:862:20: warning: no previous prototype for 'arch_task_cache_init' [-Wmissing-prototypes]
862 | void __init __weak arch_task_cache_init(void) { }
| ^~~~~~~~~~~~~~~~~~~~
kernel/fork.c:957:12: warning: no previous prototype for 'arch_dup_task_struct' [-Wmissing-prototypes]
957 | int __weak arch_dup_task_struct(struct task_struct *dst,
| ^~~~~~~~~~~~~~~~~~~~
--
In file included from include/linux/io_uring.h:7,
from kernel/exit.c:67:
>> include/uapi/linux/io_uring.h:628:41: error: flexible array member in union
628 | struct io_uring_buf bufs[];
| ^~~~
kernel/exit.c:1901:13: warning: no previous prototype for 'abort' [-Wmissing-prototypes]
1901 | __weak void abort(void)
| ^~~~~
--
In file included from include/linux/io_uring.h:7,
from fs/exec.c:64:
>> include/uapi/linux/io_uring.h:628:41: error: flexible array member in union
628 | struct io_uring_buf bufs[];
| ^~~~
--
In file included from include/linux/io_uring.h:7,
from io_uring/io_uring.c:72:
>> include/uapi/linux/io_uring.h:628:41: error: flexible array member in union
628 | struct io_uring_buf bufs[];
| ^~~~
io_uring/io_uring.c: In function '__io_submit_flush_completions':
io_uring/io_uring.c:1443:40: warning: variable 'prev' set but not used [-Wunused-but-set-variable]
1443 | struct io_wq_work_node *node, *prev;
| ^~~~
--
In file included from include/linux/io_uring.h:7,
from io_uring/kbuf.c:10:
>> include/uapi/linux/io_uring.h:628:41: error: flexible array member in union
628 | struct io_uring_buf bufs[];
| ^~~~
In file included from include/linux/container_of.h:5,
from include/linux/kernel.h:21,
from io_uring/kbuf.c:2:
io_uring/kbuf.c: In function 'io_register_pbuf_ring':
include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/compiler.h:232:33: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
232 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
| ^~~~~~~~~~~~~~~~~
include/linux/overflow.h:277:50: note: in expansion of macro '__must_be_array'
277 | (count) * sizeof(*(p)->member) + __must_be_array((p)->member), \
| ^~~~~~~~~~~~~~~
include/linux/overflow.h:293:32: note: in expansion of macro 'flex_array_size'
293 | sizeof(*(p)) + flex_array_size(p, member, count), \
| ^~~~~~~~~~~~~~~
io_uring/kbuf.c:508:30: note: in expansion of macro 'struct_size'
508 | struct_size(br, bufs, reg.ring_entries),
| ^~~~~~~~~~~
include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/compiler.h:232:33: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
232 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
| ^~~~~~~~~~~~~~~~~
include/linux/overflow.h:278:56: note: in expansion of macro '__must_be_array'
278 | size_mul(count, sizeof(*(p)->member) + __must_be_array((p)->member)))
| ^~~~~~~~~~~~~~~
include/linux/overflow.h:293:32: note: in expansion of macro 'flex_array_size'
293 | sizeof(*(p)) + flex_array_size(p, member, count), \
| ^~~~~~~~~~~~~~~
io_uring/kbuf.c:508:30: note: in expansion of macro 'struct_size'
508 | struct_size(br, bufs, reg.ring_entries),
| ^~~~~~~~~~~
include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/compiler.h:232:33: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
232 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
| ^~~~~~~~~~~~~~~~~
include/linux/overflow.h:277:50: note: in expansion of macro '__must_be_array'
277 | (count) * sizeof(*(p)->member) + __must_be_array((p)->member), \
| ^~~~~~~~~~~~~~~
include/linux/overflow.h:294:40: note: in expansion of macro 'flex_array_size'
294 | size_add(sizeof(*(p)), flex_array_size(p, member, count)))
| ^~~~~~~~~~~~~~~
io_uring/kbuf.c:508:30: note: in expansion of macro 'struct_size'
508 | struct_size(br, bufs, reg.ring_entries),
| ^~~~~~~~~~~
include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/compiler.h:232:33: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
232 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
| ^~~~~~~~~~~~~~~~~
include/linux/overflow.h:278:56: note: in expansion of macro '__must_be_array'
278 | size_mul(count, sizeof(*(p)->member) + __must_be_array((p)->member)))
| ^~~~~~~~~~~~~~~
include/linux/overflow.h:294:40: note: in expansion of macro 'flex_array_size'
294 | size_add(sizeof(*(p)), flex_array_size(p, member, count)))
| ^~~~~~~~~~~~~~~
io_uring/kbuf.c:508:30: note: in expansion of macro 'struct_size'
508 | struct_size(br, bufs, reg.ring_entries),
| ^~~~~~~~~~~
vim +628 include/uapi/linux/io_uring.h
615
616 struct io_uring_buf_ring {
617 union {
618 /*
619 * To avoid spilling into more pages than we need to, the
620 * ring tail is overlaid with the io_uring_buf->resv field.
621 */
622 struct {
623 __u64 resv1;
624 __u32 resv2;
625 __u16 resv3;
626 __u16 tail;
627 };
> 628 struct io_uring_buf bufs[];
629 };
630 };
631
On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote: > Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's > "bufs" with a flexible array member. (How is the size of this array > verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: > > In function 'io_ring_buffer_select', > inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: > io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] > 141 | buf = &br->bufs[head]; > | ^~~~~~~~~~~~~~~ > In file included from include/linux/io_uring.h:7, > from io_uring/kbuf.c:10: > include/uapi/linux/io_uring.h: In function 'io_buffer_select': > include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' > 628 | struct io_uring_buf bufs[0]; > | ^~~~ > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Pavel Begunkov <asml.silence@gmail.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: stable@vger.kernel.org Build problem aside, why is this a stable kernel issue? thanks, greg k-h
On Thu, Jan 05, 2023 at 08:39:48AM +0100, Greg KH wrote: > On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote: > > Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's > > "bufs" with a flexible array member. (How is the size of this array > > verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: > > > > In function 'io_ring_buffer_select', > > inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: > > io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] > > 141 | buf = &br->bufs[head]; > > | ^~~~~~~~~~~~~~~ > > In file included from include/linux/io_uring.h:7, > > from io_uring/kbuf.c:10: > > include/uapi/linux/io_uring.h: In function 'io_buffer_select': > > include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' > > 628 | struct io_uring_buf bufs[0]; > > | ^~~~ > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > > Cc: Jens Axboe <axboe@kernel.dk> > > Cc: Pavel Begunkov <asml.silence@gmail.com> > > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > > Cc: stable@vger.kernel.org > > Build problem aside, why is this a stable kernel issue? My thinking was that since this is technically a UAPI change, it'd be best to get it changed as widely as possible.
On Thu, Jan 05, 2023 at 10:04:19AM -0800, Kees Cook wrote: > On Thu, Jan 05, 2023 at 08:39:48AM +0100, Greg KH wrote: > > On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote: > > > Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's > > > "bufs" with a flexible array member. (How is the size of this array > > > verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: > > > > > > In function 'io_ring_buffer_select', > > > inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: > > > io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] > > > 141 | buf = &br->bufs[head]; > > > | ^~~~~~~~~~~~~~~ > > > In file included from include/linux/io_uring.h:7, > > > from io_uring/kbuf.c:10: > > > include/uapi/linux/io_uring.h: In function 'io_buffer_select': > > > include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' > > > 628 | struct io_uring_buf bufs[0]; > > > | ^~~~ > > > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > > > > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > > > Cc: Jens Axboe <axboe@kernel.dk> > > > Cc: Pavel Begunkov <asml.silence@gmail.com> > > > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > > > Cc: stable@vger.kernel.org > > > > Build problem aside, why is this a stable kernel issue? > > My thinking was that since this is technically a UAPI change, it'd be > best to get it changed as widely as possible. You can't break the uapi, so it should be the same with or without your change right? confused, greg k-h
[resend -- I failed to CC the thread] On Thu, Jan 05, 2023 at 08:38:01PM +0100, Greg KH wrote: > On Thu, Jan 05, 2023 at 10:04:19AM -0800, Kees Cook wrote: > > On Thu, Jan 05, 2023 at 08:39:48AM +0100, Greg KH wrote: > > > On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote: > > > > Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's > > > > "bufs" with a flexible array member. (How is the size of this array > > > > verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: > > > > > > > > In function 'io_ring_buffer_select', > > > > inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: > > > > io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] > > > > 141 | buf = &br->bufs[head]; > > > > | ^~~~~~~~~~~~~~~ > > > > In file included from include/linux/io_uring.h:7, > > > > from io_uring/kbuf.c:10: > > > > include/uapi/linux/io_uring.h: In function 'io_buffer_select': > > > > include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' > > > > 628 | struct io_uring_buf bufs[0]; > > > > | ^~~~ > > > > > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays > > > > > > > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > > > > Cc: Jens Axboe <axboe@kernel.dk> > > > > Cc: Pavel Begunkov <asml.silence@gmail.com> > > > > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > > > > Cc: stable@vger.kernel.org > > > > > > Build problem aside, why is this a stable kernel issue? > > > > My thinking was that since this is technically a UAPI change, it'd be > > best to get it changed as widely as possible. > > You can't break the uapi, so it should be the same with or without your > change right? > > confused, Correct -- but we've had a hard time finding breakages (with extremely weird stuff like non-C .h file scrapers) due to the lag between making UAPI changes like this. Anyway, I can drop the CC stable if it's more sensible.
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 2780bce62faf..9d8861899cde 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -625,7 +625,7 @@ struct io_uring_buf_ring { __u16 resv3; __u16 tail; }; - struct io_uring_buf bufs[0]; + struct io_uring_buf bufs[]; }; };
Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's "bufs" with a flexible array member. (How is the size of this array verified?) Detected with GCC 13, using -fstrict-flex-arrays=3: In function 'io_ring_buffer_select', inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] 141 | buf = &br->bufs[head]; | ^~~~~~~~~~~~~~~ In file included from include/linux/io_uring.h:7, from io_uring/kbuf.c:10: include/uapi/linux/io_uring.h: In function 'io_buffer_select': include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' 628 | struct io_uring_buf bufs[0]; | ^~~~ [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Cc: Jens Axboe <axboe@kernel.dk> Cc: Pavel Begunkov <asml.silence@gmail.com> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: stable@vger.kernel.org Cc: io-uring@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- include/uapi/linux/io_uring.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)