CVE-2026-98600Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame()

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame() While rfcomm_recv_frame() verifies that skb->len is at least sizeof(*hdr) + 1 (4 bytes: 3-byte header + 1-byte FCS), an RFCOMM frame with an extended 2-byte length field (!__test_ea(hdr->len)) has a 4-byte header plus a 1-byte FCS (5 bytes minimum, sizeof(*hdr) + 2). When a 4-byte RFCOMM frame with EA == 0 arrives: 1. The initial skb->len < sizeof(*hdr) + 1 check passes (4 < 4 is false). 2. Trimming the FCS byte decrements skb->len to 3. 3. If __check_fcs() succeeds, skb_pull(skb, 4) fails (4 > 3) and returns NULL without advancing skb->data. 4. Because the return value of skb_pull() is ignored, the un-pulled 3-byte struct rfcomm_hdr remains at skb->data and is either queued as application payload via rfcomm_recv_data() or parsed as a multiplexer control command via rfcomm_recv_mcc() on DLCI 0. Fix this by extending the length check in rfcomm_recv_frame() to also require skb->len >= sizeof(*hdr) + 2 when !__test_ea(hdr->len).

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/76876fd26569302d26d91cbe8b75fa8e66cf8969
• https://git.kernel.org/stable/c/97711b964877242933484989224a3c4c5d88a5ee
• https://git.kernel.org/stable/c/7a1781a2f3a9667b3065d402d1f11986a2363e08
• https://git.kernel.org/stable/c/c25587fa26761e623198b4f47151fe79d09ccde6
• https://git.kernel.org/stable/c/71ccacde407b7d8f0ef48974a0d2524602fd5c44
• https://git.kernel.org/stable/c/be00deee60044ffa820f9436415caeb665b2cda0
• https://git.kernel.org/stable/c/9240fc1f2cde5331c61608da21b00394602ca762
• https://git.kernel.org/stable/c/6d91041bb38b97e2feb625123cc0529d7b83a0e1