In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net: stmmac: xgmac2: disable RBUE in default RX interrupt mask<\/p>\n
Enabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive
\nand can trigger a MAC interrupt storm under heavy RX pressure. When the
\nDMA runs out of RX descriptors it fires RBUE continuously until software
\nrefills the ring.<\/p>\n
However, RBUE is redundant: the normal RX completion interrupt (RIE)
\nalready triggers NAPI, which processes completed descriptors and refills
\nthe ring, causing the DMA to resume. The RBUE handler itself only sets
\nhandle_rx – the same outcome as RIE.<\/p>\n
On Agilex5 under heavy RX pressure, the MAC interrupt (which includes
\nRBUE) was observed firing 1,821,811,555 times against only 2,618,627
\nactual RX completions – a ~695x ratio – confirming the severity of the
\nstorm.<\/p>\n
RBUE does not provide OOM recovery. If page_pool is exhausted,
\nstmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays
\nsuspended, and RBUE fires again on the next NAPI completion – a storm
\nwith no forward progress. This patch trades that storm for a clean
\nstall with the same RX outcome. Proper OOM recovery is a pre-existing
\ngap outside the scope of this fix.<\/p>\n
Note: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool
\ncounter will always read 0 on XGMAC2 devices. This behaviour is already
\ninconsistent across DWMAC core versions.<\/p>\n
Remove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX
\nto prevent the interrupt storm while keeping normal RX handling intact.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net: stmmac: xgmac2: disable RBUE in default RX interrupt mask<\/p>\n
Enabling the RX Buffer Unavailable (RBUE) interrupt is counterprodu<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-28645","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/28645","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28645"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28645"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28645"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}