* [PATCH][next] brcmfmac: Replace zero-length array with flexible-array member
@ 2020-02-25 2:08 Gustavo A. R. Silva
2020-03-06 10:26 ` Arend Van Spriel
2020-03-23 17:12 ` Kalle Valo
0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2020-02-25 2:08 UTC (permalink / raw)
To: Arend van Spriel, Franky Lin, Hante Meuleman, Chi-Hsien Lin,
Wright Feng, Kalle Valo, David S. Miller
Cc: linux-wireless, brcm80211-dev-list.pdl, brcm80211-dev-list,
netdev, linux-kernel, Gustavo A. R. Silva
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 <gustavo@embeddedor.com>
---
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[];
};
/**
--
2.25.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH][next] brcmfmac: Replace zero-length array with flexible-array member
2020-02-25 2:08 [PATCH][next] brcmfmac: Replace zero-length array with flexible-array member Gustavo A. R. Silva
@ 2020-03-06 10:26 ` Arend Van Spriel
2020-03-23 17:12 ` Kalle Valo
1 sibling, 0 replies; 3+ messages in thread
From: Arend Van Spriel @ 2020-03-06 10:26 UTC (permalink / raw)
To: Gustavo A. R. Silva, Franky Lin, Hante Meuleman, Chi-Hsien Lin,
Wright Feng, Kalle Valo, David S. Miller
Cc: linux-wireless, brcm80211-dev-list.pdl, brcm80211-dev-list,
netdev, linux-kernel
On 2/25/2020 3:08 AM, Gustavo A. R. Silva wrote:
> 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:
[...]
> "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")
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> 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(-)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH][next] brcmfmac: Replace zero-length array with flexible-array member
2020-02-25 2:08 [PATCH][next] brcmfmac: Replace zero-length array with flexible-array member Gustavo A. R. Silva
2020-03-06 10:26 ` Arend Van Spriel
@ 2020-03-23 17:12 ` Kalle Valo
1 sibling, 0 replies; 3+ messages in thread
From: Kalle Valo @ 2020-03-23 17:12 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Arend van Spriel, Franky Lin, Hante Meuleman, Chi-Hsien Lin,
Wright Feng, David S. Miller, linux-wireless,
brcm80211-dev-list.pdl, brcm80211-dev-list, netdev, linux-kernel,
Gustavo A. R. Silva
"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:
> 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 <gustavo@embeddedor.com>
> Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Patch applied to wireless-drivers-next.git, thanks.
232c897eb5ca brcmfmac: Replace zero-length array with flexible-array member
--
https://patchwork.kernel.org/patch/11402413/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
^ permalink raw reply [flat|nested] 3+ messages in thread
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