Date: Thu, 01 Dec 2022 02:04:53 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 268092] ixgbe: if_ixv driver have mismatched Rx buffer size and rx_mbuf_sz Message-ID: <bug-268092-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D268092 Bug ID: 268092 Summary: ixgbe: if_ixv driver have mismatched Rx buffer size and rx_mbuf_sz Product: Base System Version: 12.2-STABLE Hardware: amd64 OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: nkumarababu@gmail.com If MTU of the if_ixv VF driver is configured between 1501 and 2030, and if a peer box have bigger MTU and sends a packet bigger than MTU into this guest, kernel could crashes.=20 Here is my understanding : There are 2 buffers involved for Rx process. One for the DMA(bufsz) and another(rx_mbuf_sz) for sending that packet to netstack. In if_ixv driver, bufsz is set to 4096 if MTU is more than the default MTU: 1500. Whereas rx_mbuf_sz is set to 2048, for upto MTU 2030 (Calculation is based on frame size: 18). Because of this, for MTU upto 1500, both rx_mbuf_sz & bufsz is 2048. And for MTU above 2031, both=20 rx_mbuf_sz & bufsz is 4096. Whereas for MTU 1501 to 2030, rx_mbuf_sz=20 will be 2048 and bufsz is 4096.=20 So for MTU between 1501 and 2030, if the peer box have bigger MTU and=20 sends a bigger packet, there is a mismatch between what's written to=20 the Rx buffers and what's sent to netstack. And when that memory beyond allocated 2048 is accessed, kernel crashes.=20 Ideally, bufsz should be based on rx_mbuf_sz (This is calculated right before configuring Rx settings).=20 I could crash the box my setting MTU between 1501 and 2030 and sending send= ing 8k sized ping packet very consistently and with this below fix to match bufsz & rx_mbuf_sz, could verify that no crash occurred.=20 --- a/sys/dev/ixgbe/if_ixv.c +++ b/sys/dev/ixgbe/if_ixv.c @@ -1368,7 +1376,7 @@ ixv_initialize_receive_units(if_ctx_t ctx) struct ix_rx_queue *que =3D adapter->rx_queues; u32 bufsz, psrtype; - if (if_getmtu(ifp) > ETHERMTU) + if (adapter->rx_mbuf_sz > 2048) bufsz =3D 4096 >> IXGBE_SRRCTL_BSIZEPKT_SHIFT; else bufsz =3D 2048 >> IXGBE_SRRCTL_BSIZEPKT_SHIFT; --=20 You are receiving this mail because: You are the assignee for the bug.=
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