On 21/08/24 14:26, Andy Shevchenko wrote:
On Thu, Feb 02, 2023 at 07:32:00PM -0600, Gustavo A. R. Silva wrote:
One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element arrays with flexible-array
members in multiple structures.
This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].
This results in no differences in binary output.
Sorry for blast from the past, but I have a question here.
This change seems converts many of the flexible arrays in this driver.
But what's behind this one?
struct host_cmd_ds_802_11_scan_ext {
u32 reserved;
u8 tlv_buffer[1];
} __packed;
AFAIU this needs also some care. On the real machine I have got this
elo 16 17:51:58 surfacebook kernel: ------------[ cut here ]------------
elo 16 17:51:58 surfacebook kernel: memcpy: detected field-spanning write (size 243) of single field "ext_scan->tlv_buffer" at drivers/net/wireless/marvell/mwifiex/scan.c:2239 (size 1)
elo 16 17:51:58 surfacebook kernel: WARNING: CPU: 0 PID: 498 at drivers/net/wireless/marvell/mwifiex/scan.c:2239 mwifiex_cmd_802_11_scan_ext+0x83/0x90 [mwifiex]
which leads to
memcpy(ext_scan->tlv_buffer, scan_cfg->tlv_buf, scan_cfg->tlv_buf_len);
but the code allocates 2k or more for the command buffer, so this seems
quite enough for 243 bytes.
I think this would do it:
diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
index e91def0afa14..d03129d5d24e 100644
--- a/drivers/net/wireless/marvell/mwifiex/fw.h
+++ b/drivers/net/wireless/marvell/mwifiex/fw.h
@@ -1627,7 +1627,7 @@ struct host_cmd_ds_802_11_scan_rsp {
struct host_cmd_ds_802_11_scan_ext {
u32 reserved;
- u8 tlv_buffer[1];
+ u8 tlv_buffer[];
} __packed;
struct mwifiex_ie_types_bss_mode {
diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c
index e782d652cb93..f7153472e2a2 100644
--- a/drivers/net/wireless/marvell/mwifiex/scan.c
+++ b/drivers/net/wireless/marvell/mwifiex/scan.c
@@ -2536,8 +2536,7 @@ int mwifiex_ret_802_11_scan_ext(struct mwifiex_private *priv,
ext_scan_resp = &resp->params.ext_scan;
tlv = (void *)ext_scan_resp->tlv_buffer;
- buf_left = le16_to_cpu(resp->size) - (sizeof(*ext_scan_resp) + S_DS_GEN
- - 1);
+ buf_left = le16_to_cpu(resp->size) - (sizeof(*ext_scan_resp) + S_DS_GEN);
while (buf_left >= sizeof(struct mwifiex_ie_types_header)) {
type = le16_to_cpu(tlv->type);
--
Gustavo
