misc: bcm-vk: Annotate struct bcm_vk_wkent with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct bcm_vk_wkent.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Scott Branden <scott.branden@broadcom.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175057.work.558-kees@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/bcm-vk/bcm_vk_msg.c b/drivers/misc/bcm-vk/bcm_vk_msg.c
index e17d81231ea6dab4c496ea2c8cad2a053e306972..1f42d1d5a630a23734878fe6a4414cdb14495849 100644 (file)
--- a/drivers/misc/bcm-vk/bcm_vk_msg.c
+++ b/drivers/misc/bcm-vk/bcm_vk_msg.c
@@ -703,12 +703,12 @@ int bcm_vk_send_shutdown_msg(struct bcm_vk *vk, u32 shut_type,
        entry = kzalloc(struct_size(entry, to_v_msg, 1), GFP_KERNEL);
        if (!entry)
                return -ENOMEM;
+       entry->to_v_blks = 1;   /* always 1 block */
 
        /* fill up necessary data */
        entry->to_v_msg[0].function_id = VK_FID_SHUTDOWN;
        set_q_num(&entry->to_v_msg[0], q_num);
        set_msg_id(&entry->to_v_msg[0], VK_SIMPLEX_MSG_ID);
-       entry->to_v_blks = 1; /* always 1 block */
 
        entry->to_v_msg[0].cmd = shut_type;
        entry->to_v_msg[0].arg = pid;

diff --git a/drivers/misc/bcm-vk/bcm_vk_msg.h b/drivers/misc/bcm-vk/bcm_vk_msg.h
index 56784c8896d8734da196a4ae5e2349307ecc0117..157495e48f15ac7e1eeb73a768c496fbdc33efbb 100644 (file)
--- a/drivers/misc/bcm-vk/bcm_vk_msg.h
+++ b/drivers/misc/bcm-vk/bcm_vk_msg.h
@@ -116,7 +116,7 @@ struct bcm_vk_wkent {
        u32 usr_msg_id;
        u32 to_v_blks;
        u32 seq_num;
-       struct vk_msg_blk to_v_msg[];
+       struct vk_msg_blk to_v_msg[] __counted_by(to_v_blks);
 };
 
 /* queue stats counters */