[PW_SID:1108158] Bluetooth: L2CAP: validate connectionless PSM length#294
[PW_SID:1108158] Bluetooth: L2CAP: validate connectionless PSM length#294BluezTestBot wants to merge 1 commit into
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Connectionless L2CAP frames carry a two-byte PSM at the start of the payload. l2cap_recv_frame() currently reads that PSM unconditionally after validating only the outer L2CAP length. A malformed connectionless frame with a zero- or one-byte payload can therefore make the parser read beyond the advertised skb payload and use tailroom bytes as part of the PSM. A VHCI-backed QEMU reproducer injected a one-byte connectionless payload and reached the unchecked read. Reject connectionless frames that cannot contain the PSM before reading or pulling it. This preserves all valid connectionless frames while dropping only structurally incomplete packets. Assisted-by: Codex:gpt-5.5-cyber-preview Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
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Connectionless L2CAP frames carry a two-byte PSM at the start of the
payload. l2cap_recv_frame() currently reads that PSM unconditionally
after validating only the outer L2CAP length.
A malformed connectionless frame with a zero- or one-byte payload can
therefore make the parser read beyond the advertised skb payload and use
tailroom bytes as part of the PSM. A VHCI-backed QEMU reproducer
injected a one-byte connectionless payload and reached the unchecked
read.
Reject connectionless frames that cannot contain the PSM before reading
or pulling it. This preserves all valid connectionless frames while
dropping only structurally incomplete packets.
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius sam.moelius@trailofbits.com
net/bluetooth/l2cap_core.c | 5 +++++
1 file changed, 5 insertions(+)