[PW_SID:1153829] [v2,1/2] Bluetooth: L2CAP: fix out-of-bounds write in l2cap_ecred_connect - #667
[PW_SID:1153829] [v2,1/2] Bluetooth: L2CAP: fix out-of-bounds write in l2cap_ecred_connect#667BluezTestBot wants to merge 2 commits into
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l2cap_chan_connect() tries to ensure there are no more than L2CAP_ECRED_CONN_SCID_MAX pending ECRED channels, so they fit in the same L2CAP_ECRED_CONN_REQ that l2cap_ecred_connect() constructs. However, the check only counts deferred channels. If 6 L2CAP sockets are connected at the same time in order DDDDND (D=deferred, N=non-deferred), the last can bump the total to max+1. It results to one __le16 written out of bounds of the scid array, and an invalid ECRED_CONN_REQ being sent. Fix by leaving room for the non-deferred pending ECRED channels in the counting in l2cap_chan_connect(), so the limit can't be exceeded. Move counting under same critical section where the channel is added. Although race conditions involving this appear unreachable, it's easier to see. Also add WARN_ON_ONCE check in l2cap_ecred_defer_connect() to make this less brittle. Fixes: da49b60 ("Bluetooth: L2CAP: Use DEFER_SETUP to group ECRED connections") Signed-off-by: Pauli Virtanen <pav@iki.fi>
l2cap_ecred_defer_connect() clears FLAG_DEFER_SETUP also for channels with different PID/PSM, which will not be added to the same ECRED_CONN_REQ in any case. Consequently, only one ECRED connection group can work at a time although it appears intended they would be separate for each PID/PSM combination. Fix by clearing FLAG_DEFER_SETUP only for the connections that could be added in the request. Retain test_bit(FLAG_DEFER_SETUP) before calling get_peer_pid as it may be NULL otherwise. Fixes: da49b60 ("Bluetooth: L2CAP: Use DEFER_SETUP to group ECRED connections") Signed-off-by: Pauli Virtanen <pav@iki.fi>
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l2cap_chan_connect() tries to ensure there are no more than
L2CAP_ECRED_CONN_SCID_MAX pending ECRED channels, so they fit in the
same L2CAP_ECRED_CONN_REQ that l2cap_ecred_connect() constructs.
However, the check only counts deferred channels. If 6 L2CAP sockets
are connected at the same time in order DDDDND (D=deferred,
N=non-deferred), the last can bump the total to max+1. It results to
one __le16 written out of bounds of the scid array, and an invalid
ECRED_CONN_REQ being sent.
Fix by leaving room for the non-deferred pending ECRED channels in the
counting in l2cap_chan_connect(), so the limit can't be exceeded.
Move counting under same critical section where the channel is added.
Although race conditions involving this appear unreachable, it's easier
to see.
Also add WARN_ON_ONCE check in l2cap_ecred_defer_connect() to make this
less brittle.
Fixes: da49b60 ("Bluetooth: L2CAP: Use DEFER_SETUP to group ECRED connections")
Signed-off-by: Pauli Virtanen pav@iki.fi
Notes:
Bug found as pre-existing in sashiko.dev report
net/bluetooth/l2cap_core.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)