If a (legacy) client requested a wiphy dump but did not provide the
NL80211_ATTR_SPLIT_WIPHY_DUMP attribute, the dump was supposed to be
composed of purely non-split NEW_WIPHY messages, with 1 wiphy per
message. At least this was the intent after commit:
3713b4e364ef ("nl80211: allow splitting wiphy information in dumps")
However, in reality the non-split dumps were broken very shortly after.
Perhaps around commit:
fe1abafd942f ("nl80211: re-add channel width and extended capa advertising")
The reason for the bug is a missing setting of split_start to 0 in the
case of a non-split dump.
Here is a sample non-split dump performed on kernel 4.19, some parts
were cut for brevity:
< Request: Get Wiphy (0x01) len 0 [ack,0x300]
> Result: New Wiphy (0x03) len 3496 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
<snip>
> Result: New Wiphy (0x03) len 68 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
Extended Capabilities: len 8
Capability: bit 2: Extended channel switching
Capability: bit 62: Opmode Notification
Extended Capabilities Mask: len 8
04 00 00 00 00 00 00 40 .......@
VHT Capability Mask: len 12
f0 1f 80 33 ff ff 00 00 ff ff 00 00 ...3........
> Result: New Wiphy (0x03) len 28 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
> Result: New Wiphy (0x03) len 28 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
> Result: New Wiphy (0x03) len 52 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
Max CSA Counters: len 1
02 .
Scheduled Scan Maximum Requests: len 4
01 00 00 00 ....
Extended Features: len 4
02 02 00 04 ....
> Result: New Wiphy (0x03) len 36 [multi]
Wiphy: 0 (0x00000000)
Wiphy Name: phy0
Generation: 1 (0x00000001)
Reserved: len 4
00 00 00 00 ....
> Complete: Get Wiphy (0x01) len 4 [multi]
Status: 0
Signed-off-by: Denis Kenzior <denkenz@xxxxxxxxx>
---
net/wireless/nl80211.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 3e30e18d1d89..ff6200fcd492 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2191,6 +2191,9 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev,
* but break unconditionally so unsplit data stops here.
*/
state->split_start++;
+
+ if (!state->split)
+ state->split_start = 0;
break;
case 9:
if (rdev->wiphy.extended_capabilities &&
--
2.19.2
