From: Johan Hedberg <johan.hedberg@xxxxxxxxx>
In some cases the current 300ms delay is not enough for the remote to
receive the keys, as can be witnessed by the following log:
> ACL Data RX: Handle 64 flags 0x02 dlen 21 [hci1] 231.414217
SMP: Signing Information (0x0a) len 16
Signature key: 555bb66b7ab3abc9d5c287c97fe6eb29
< ACL Data TX: Handle 64 flags 0x00 dlen 21 [hci1] 231.414414
SMP: Encryption Information (0x06) len 16
Long term key: 2a7cdc233c9a4b1f3ed31dd9843fea29
< ACL Data TX: Handle 64 flags 0x00 dlen 15 [hci1] 231.414466
SMP: Master Identification (0x07) len 10
EDIV: 0xeccc
Rand: 0x322e0ef50bd9308a
< ACL Data TX: Handle 64 flags 0x00 dlen 21 [hci1] 231.414505
SMP: Signing Information (0x0a) len 16
Signature key: bbda1b2076e2325aa66fbcdd5388f745
> HCI Event: Number of Completed Packets (0x13) plen 5 [hci1] 231.483130
Num handles: 1
Handle: 64
Count: 2
< HCI Command: LE Start Encryption (0x08|0x0019) plen 28 [hci1] 231.664211
Handle: 64
Random number: 0x5052ad2b75fed54b
Encrypted diversifier: 0xb7c2
Long term key: a336ede66711b49a84bde9b41426692e
> HCI Event: Command Status (0x0f) plen 4 [hci1] 231.666937
LE Start Encryption (0x08|0x0019) ncmd 1
Status: Success (0x00)
> HCI Event: Number of Completed Packets (0x13) plen 5 [hci1] 231.712646
Num handles: 1
Handle: 64
Count: 1
> HCI Event: Disconnect Complete (0x05) plen 4 [hci1] 232.562587
Status: Success (0x00)
Handle: 64
Reason: Remote User Terminated Connection (0x13)
As can be seen, the last key (Signing Information) is sent at 231.414505
but the completed packets event for it comes only at 231.712646,
i.e.roughly 298ms later. When introducing HCI latencies to the mix this
it too small of a margin to trust that the remote side has properly
processed the keys.
To have a better margin of error this patch increases the delay to
500ms.
Signed-off-by: Johan Hedberg <johan.hedberg@xxxxxxxxx>
---
net/bluetooth/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index ed1c9547ba6e..a1a73bf9b735 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -31,7 +31,7 @@
#include "smp.h"
-#define SMP_TIMEOUT msecs_to_jiffies(30000)
+#define SMP_TIMEOUT msecs_to_jiffies(50000)
#define AUTH_REQ_MASK 0x07
--
1.8.5.3
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