CVE-2026-98107Bluetooth: L2CAP: fix out-of-bounds write in l2cap_ecred_connect

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix out-of-bounds write in l2cap_ecred_connect 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fabc5e04f123225daf980d03f2c5a05e7f0f0a7f
• https://git.kernel.org/stable/c/ce0927eb3ee2939fab5ce3f9334bfd2fafb38481
• https://git.kernel.org/stable/c/6da5c0331fc3ef0c7b8df8269523fc3b2cce1e65
• https://git.kernel.org/stable/c/df8c3af6132640da4788e96a02d653e642059803
• https://git.kernel.org/stable/c/56c2b5831d39dc84aad2573dc3e197af1a872a05