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Kees Cook 52cc98d1cb stddef: Introduce DECLARE_FLEX_ARRAY() helper
commit 3080ea5553cc909b000d1f1d964a9041962f2c5b upstream.

There are many places where kernel code wants to have several different
typed trailing flexible arrays. This would normally be done with multiple
flexible arrays in a union, but since GCC and Clang don't (on the surface)
allow this, there have been many open-coded workarounds, usually involving
neighboring 0-element arrays at the end of a structure. For example,
instead of something like this:

struct thing {
	...
	union {
		struct type1 foo[];
		struct type2 bar[];
	};
};

code works around the compiler with:

struct thing {
	...
	struct type1 foo[0];
	struct type2 bar[];
};

Another case is when a flexible array is wanted as the single member
within a struct (which itself is usually in a union). For example, this
would be worked around as:

union many {
	...
	struct {
		struct type3 baz[0];
	};
};

These kinds of work-arounds cause problems with size checks against such
zero-element arrays (for example when building with -Warray-bounds and
-Wzero-length-bounds, and with the coming FORTIFY_SOURCE improvements),
so they must all be converted to "real" flexible arrays, avoiding warnings
like this:

fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree':
fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds]
  209 |    anode->btree.u.internal[0].down = cpu_to_le32(a);
      |    ~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from fs/hpfs/hpfs_fn.h:26,
                 from fs/hpfs/anode.c:10:
fs/hpfs/hpfs.h:412:32: note: while referencing 'internal'
  412 |     struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving
      |                                ^~~~~~~~

drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg':
drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds]
  360 |  tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len];
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22,
                 from drivers/net/can/usb/etas_es58x/es58x_fd.c:17:
drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg'
  231 |   u8 raw_msg[0];
      |      ^~~~~~~

However, it _is_ entirely possible to have one or more flexible arrays
in a struct or union: it just has to be in another struct. And since it
cannot be alone in a struct, such a struct must have at least 1 other
named member -- but that member can be zero sized. Wrap all this nonsense
into the new DECLARE_FLEX_ARRAY() in support of having flexible arrays
in unions (or alone in a struct).

As with struct_group(), since this is needed in UAPI headers as well,
implement the core there, with a non-UAPI wrapper.

Additionally update kernel-doc to understand its existence.

https://github.com/KSPP/linux/issues/137

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-18 12:12:59 +01:00
.github/workflows Add build stuff 2024-06-15 16:48:05 -03:00
android Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
arch parisc/firmware: Fix F-extend for PDC addresses 2024-11-18 12:12:56 +01:00
block block: Remove special-casing of compound pages 2024-11-18 12:12:59 +01:00
certs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crypto crypto: api - Disallow identical driver names 2024-11-18 12:12:55 +01:00
Documentation rename(): fix the locking of subdirectories 2024-11-18 12:12:59 +01:00
drivers nouveau/vmm: don't set addr on the fail path to avoid warning 2024-11-18 12:12:59 +01:00
firmware/tsp_goodix Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs rename(): fix the locking of subdirectories 2024-11-18 12:12:59 +01:00
gki Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
include stddef: Introduce DECLARE_FLEX_ARRAY() helper 2024-11-18 12:12:59 +01:00
init rootfs: Fix support for rootfstype= when root= is given 2024-11-18 12:12:47 +01:00
io_uring io_uring/rw: ensure io->bytes_done is always initialized 2024-11-18 12:12:47 +01:00
ipc Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kernel async: Introduce async_schedule_dev_nocall() 2024-11-18 12:12:56 +01:00
kernel_build kernel_build: build.sh: Fixed kernel version on zips/tars 2024-11-17 22:12:20 +01:00
kunitconfigs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
lib ida: Fix crash in ida_free when the bitmap is empty 2024-11-18 12:12:17 +01:00
LICENSES Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
mm mm: fix unmap_mapping_range high bits shift bug 2024-11-18 12:12:08 +01:00
net ethtool: netlink: Add missing ethnl_ops_begin/complete 2024-11-18 12:12:51 +01:00
samples Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scripts stddef: Introduce DECLARE_FLEX_ARRAY() helper 2024-11-18 12:12:59 +01:00
security lsm: new security_file_ioctl_compat() hook 2024-11-18 12:12:58 +01:00
sound ALSA: hda/relatek: Enable Mute LED on HP Laptop 15s-fq2xxx 2024-11-18 12:12:47 +01:00
test Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
tools selftests: mlxsw: qos_pfc: Adjust the test to support 8 lanes 2024-11-18 12:12:52 +01:00
usr Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
virt Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig.arm Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.amlogic Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.arm Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.common Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.db845c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.erd8825_a25_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.erd8825_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.erd9925_evt0_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.erd9925_evt0_s5300_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.erd9925_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki-debug.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki-debug.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki.aarch64.fips140 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki.aarch64.fips140_eval_testing Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kasan Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kasan.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kasan.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kprobes Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kprobes.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kprobes.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.hikey960 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.khwasan Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.mcd Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.rockchip Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.universal2100_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.universal8825_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.universal9925_evt0_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.universal9925_s Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.sh build.sh: Disabled temporary build without debug 2024-11-17 22:32:40 +01:00
COPYING Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
CREDITS Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kbuild Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
linux-stable.sh linux-stable.sh: Added for upstream 2024-11-08 11:11:32 +01:00
MAINTAINERS Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Makefile Linux 5.10.209 2024-11-18 12:12:53 +01:00
OWNERS Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
README Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
README.md Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_boot_module_order_exynos2100.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_boot_module_order_s5e8825.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_boot_module_order_s5e9925.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e8825.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e9925.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e9925_b0s.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e9925_g0s.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e9925_r0s.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.
  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)