Commit a0947081 authored Oct 01, 2020 by Gustavo A. R. Silva Committed by Borislav Petkov Oct 01, 2020

x86/uv/time: Use a flexible array in struct uv_rtc_timer_head

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].

struct uv_rtc_timer_head contains a one-element array cpu[1]. Switch it
to a flexible array and use the struct_size() helper to calculate the
allocation size. Also, save some heap space in the process[3].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
[3] https://lore.kernel.org/lkml/20200518190114.GA7757@embeddedor/



 [ bp: Massage a bit. ]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201001145608.GA10204@embeddedor

parent a1b8638b

arch/x86/platform/uv/uv_time.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -52,7 +52,7 @@ struct uv_rtc_timer_head {
		struct {
		int lcpu; /* systemwide logical cpu number */
		u64 expires; /* next timer expiration for this cpu */
		} cpu[1];
		} cpu[];
		};

		/*
		@@ -148,9 +148,8 @@ static __init int uv_rtc_allocate_timers(void)
		struct uv_rtc_timer_head *head = blade_info[bid];

		if (!head) {
		head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
		(uv_blade_nr_possible_cpus(bid) *
		2 * sizeof(u64)),
		head = kmalloc_node(struct_size(head, cpu,
		uv_blade_nr_possible_cpus(bid)),
		GFP_KERNEL, nid);
		if (!head) {
		uv_rtc_deallocate_timers();

Admin message