From 232c897eb5ca21fce241f75b98c78f2cb36af00f Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 20:08:04 -0600 Subject: [PATCH] brcmfmac: Replace zero-length array with flexible-array member The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Acked-by: Arend van Spriel Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20200225020804.GA9428@embeddedor --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h | 2 +- drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h index 3347439543bb..46c66415b4a6 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h @@ -60,7 +60,7 @@ struct brcmf_fw_request { u16 bus_nr; u32 n_items; const char *board_type; - struct brcmf_fw_item items[0]; + struct brcmf_fw_item items[]; }; struct brcmf_fw_name { diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c index 79c8a858b6d6..a5cced2c89ac 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c @@ -32,7 +32,7 @@ struct brcmf_fweh_queue_item { u8 ifaddr[ETH_ALEN]; struct brcmf_event_msg_be emsg; u32 datalen; - u8 data[0]; + u8 data[]; }; /** -- 2.30.2