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Gustavo A. R. Silva 7de60845d7 net/ipv4/ipv6: Replace one-element arraya with flexible-array members 
[ Upstream commit db243b796439c0caba47865564d8acd18a301d18 ]

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Use an anonymous union with a couple of anonymous structs in order to
keep userspace unchanged and refactor the related code accordingly:

$ pahole -C group_filter net/ipv4/ip_sockglue.o
struct group_filter {
	union {
		struct {
			__u32      gf_interface_aux;     /*     0     4 */

			/* XXX 4 bytes hole, try to pack */

			struct __kernel_sockaddr_storage gf_group_aux; /*     8   128 */
			/* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
			__u32      gf_fmode_aux;         /*   136     4 */
			__u32      gf_numsrc_aux;        /*   140     4 */
			struct __kernel_sockaddr_storage gf_slist[1]; /*   144   128 */
		};                                       /*     0   272 */
		struct {
			__u32      gf_interface;         /*     0     4 */

			/* XXX 4 bytes hole, try to pack */

			struct __kernel_sockaddr_storage gf_group; /*     8   128 */
			/* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
			__u32      gf_fmode;             /*   136     4 */
			__u32      gf_numsrc;            /*   140     4 */
			struct __kernel_sockaddr_storage gf_slist_flex[0]; /*   144     0 */
		};                                       /*     0   144 */
	};                                               /*     0   272 */

	/* size: 272, cachelines: 5, members: 1 */
	/* last cacheline: 16 bytes */
};

$ pahole -C compat_group_filter net/ipv4/ip_sockglue.o
struct compat_group_filter {
	union {
		struct {
			__u32      gf_interface_aux;     /*     0     4 */
			struct __kernel_sockaddr_storage gf_group_aux __attribute__((__aligned__(4))); /*     4   128 */
			/* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */
			__u32      gf_fmode_aux;         /*   132     4 */
			__u32      gf_numsrc_aux;        /*   136     4 */
			struct __kernel_sockaddr_storage gf_slist[1] __attribute__((__aligned__(4))); /*   140   128 */
		} __attribute__((__packed__)) __attribute__((__aligned__(4)));                     /*     0   268 */
		struct {
			__u32      gf_interface;         /*     0     4 */
			struct __kernel_sockaddr_storage gf_group __attribute__((__aligned__(4))); /*     4   128 */
			/* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */
			__u32      gf_fmode;             /*   132     4 */
			__u32      gf_numsrc;            /*   136     4 */
			struct __kernel_sockaddr_storage gf_slist_flex[0] __attribute__((__aligned__(4))); /*   140     0 */
		} __attribute__((__packed__)) __attribute__((__aligned__(4)));                     /*     0   140 */
	} __attribute__((__aligned__(1)));               /*     0   268 */

	/* size: 268, cachelines: 5, members: 1 */
	/* forced alignments: 1 */
	/* last cacheline: 12 bytes */
} __attribute__((__packed__));

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5c3be3e0eb44 ("ipmr: fix incorrect parameter validation in the ip_mroute_getsockopt() function")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-11-19 08:44:49 +01:00
..
acpi Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
asm-generic asm-generic: qspinlock: fix queued_spin_value_unlocked() implementation 2024-11-18 12:11:56 +01:00
clocksource Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crypto crypto: af_alg - Disallow multiple in-flight AIO requests 2024-11-18 12:12:26 +01:00
drm drm: using mul_u32_u32() requires linux/math64.h 2024-11-18 12:13:21 +01:00
dt-bindings dt-bindings: clock: Update the videocc resets for sm8150 2024-11-18 12:12:41 +01:00
keys Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kunit Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kvm Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
linux PCI: Make pci_dev_is_disconnected() helper public for other drivers 2024-11-19 08:44:48 +01:00
math-emu Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
media Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
memory Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
misc Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
net net/ipv4/ipv6: Replace one-element arraya with flexible-array members 2024-11-19 08:44:49 +01:00
pcmcia Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ras Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
rdma Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scsc Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scsi scsi: core: Introduce enum scsi_disposition 2024-11-18 12:13:21 +01:00
sdp Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
soc exynos_pm_qos: Remove exynos_pm_qos_update_request_timeout() 2024-11-17 17:44:09 +01:00
sound ASoC: soc-card: Add storage for PCI SSID 2024-11-18 11:43:13 +01:00
target Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
test Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
trace tracing/net_sched: Fix tracepoints that save qdisc_dev() as a string 2024-11-18 23:19:34 +01:00
uapi net/ipv4/ipv6: Replace one-element arraya with flexible-array members 2024-11-19 08:44:49 +01:00
variant1/linux Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vdso Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
video Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
xen Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00