Module Name: src Committed By: riastradh Date: Fri Aug 12 11:25:46 UTC 2022
Modified Files: src/sys/dev/usb: usbnet.c Log Message: usbnet(9): Fix mbuf alignment and narrow bounds check. In usbnet.c rev. 1.16, usbnet_newbuf was first passed a buffer length to verify it fits within MCLBYTES. It also changed m_adj to go before, not after, setting m_len and m_pkthdr.len -- which had the effect of making the m_adj a no-op, because after MGETHDR the mbuf has zero length and m_adj stops at the length of the mbuf, so nothing was aligned as intended. To make this aligned as intended, we require the buffer length to be _below_ MCLBYTES, by ETHER_ALIGN, so there's room for the ethernet header in a maximum-length payload. Once we do that, it is safe to initialize m_len = m_pkthdr.len = ETHER_ALIGN + buflen, which is below the actual size of the mbuf (MHLEN or MCLBYTES, depending), and _then_ do m_adj to align the pointer. To generate a diff of this commit: cvs rdiff -u -r1.95 -r1.96 src/sys/dev/usb/usbnet.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.