net: usb: catc: bound the RX packet length in catc_rx_done()

Overview

In the Linux kernel, the following vulnerability has been resolved:

net: usb: catc: bound the RX packet length in catc_rx_done()

catc_rx_done() walks a multi-packet URB, reading a two-byte length from each packet header. Its bound, pkt_len > urb->actual_length, ignores the header offset and compares against the whole transfer rather than the bytes left from pkt_start, so a crafted packet header makes skb_copy_to_linear_data() read past the buffer.

A length below ETH_HLEN is also accepted, including zero, and eth_type_trans() then reads a MAC header from the uninitialised tailroom of a shorter skb. The is_f5u011 branch takes its length straight from the transfer, so a zero-length URB reaches the same path.

Track the bytes remaining from the current packet, and reject a header that does not fit, a length past what is left, and a length below an Ethernet header.

A transfer shorter than an Ethernet header, including a zero-length one, previously became a runt skb passed to netif_rx() and counted as received; it is now counted in rx_length_errors and ends the walk.

Affected

• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3942557938f846e7481f6ccb2b41ccbdee61baa1
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2f87bbd5a7bf6ee79d598f7e22cf77810d29ae87
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4cc0a8eb2f9336cfa3e4ac329bc5585ca970ced3
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 21e206dd88b3de6e36bb607dec3797c59bc3007b
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 801e21cf7dd6bcee31db907625d5045f21c9c1d9
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dd9c6f8f05170223edec2dac476606cd40d9acb7
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9d4be026bdff2c1da7b6c7e01c0a47f2df409e97
• Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9d565b6b72fe3f41fd43636e143072848105189f
• Linux 2.6.12

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.