On 3/27/2024 10:43 AM, Gustavo A. R. Silva wrote:
> 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> Changes in v2:
> - Annotate one more struct.
> - Update Subject line.
>
> v1:
> - Link: https://lore.kernel.org/linux-hardening/ZgODZOB4fOBvKl7R@neat/
>
> drivers/net/wireless/ath/wil6210/wmi.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/wil6210/wmi.h
> b/drivers/net/wireless/ath/wil6210/wmi.h
> index 71bf2ae27a98..38f64524019e 100644
> --- a/drivers/net/wireless/ath/wil6210/wmi.h
> +++ b/drivers/net/wireless/ath/wil6210/wmi.h
> @@ -474,7 +474,7 @@ struct wmi_start_scan_cmd {
> struct {
> u8 channel;
> u8 reserved;
> - } channel_list[];
> + } channel_list[] __counted_by(num_channels);
> } __packed;
does the compiler handle the actual logic where it is modifying num_channels
concurrently with writing into the array? i.e. this will be writing into
channel_list[0] when num_channels is 0:
cmd.cmd.channel_list[cmd.cmd.num_channels++].channel = ch - 1;
if that will cause a bounds check failure then suggest you change the logic so
that it updates num_channels before writing into channel_list
>
> #define WMI_MAX_PNO_SSID_NUM (16)
> @@ -3320,7 +3320,7 @@ struct wmi_set_link_monitor_cmd {
> u8 rssi_hyst;
> u8 reserved[12];
> u8 rssi_thresholds_list_size;
> - s8 rssi_thresholds_list[];
> + s8 rssi_thresholds_list[] __counted_by(rssi_thresholds_list_size);
> } __packed;
this looks ok to me, although I think there is another issue associated with
this, namely the way the code populates the rssi_thresholds_list is by
defining a separate anonymous struct:
struct {
struct wmi_set_link_monitor_cmd cmd;
s8 rssi_thold;
} __packed cmd = {
.cmd = {
.rssi_hyst = rssi_hyst,
.rssi_thresholds_list_size = 1,
},
.rssi_thold = rssi_thold,
};
I would expect gcc and clang to both complain about that s8 rssi_thold comes
after a flexible array (even though its purpose is to be the value of
rssi_thresholds_list[0])
/jeff
>
> /* wmi_link_monitor_event_type */
