GHSA-r956-xq9j-f5vj: 
In the Linux kernel, the following vulnerability has been resolved:net: fec: Use page_pool_put_full_page when freeing rx buffersThe page_pool_release_page was used when freeing rx buffers, and this
function just unmaps the page (if mapped) and does not recycle the page.
So after hundreds of down/up the eth0, the system will out of memory.
For more details, please refer to the following reproduce steps and
bug logs. To solve this issue and refer to the doc of page pool, the
page_pool_put_full_page should be used to replace page_pool_release_page.
Because this API will try to recycle the page if the page refcnt equal toAfter testing 20000 times, the issue can not be reproduced anymore
(about testing 391 times the issue will occur on i.MX8MN-EVK before).Reproduce steps:
Create the test script and run the script. The script content is as
follows:
LOOPS=20000
i=1
while [ $i -le $LOOPS ]
do
    echo "TINFO:ENET $curface up and down test $i times"
    org_macaddr=$(cat /sys/class/net/eth0/address)
    ifconfig eth0 down
    ifconfig eth0  hw ether $org_macaddr up
    i=$(expr $i + 1)
done
sleep 5
if cat /sys/class/net/eth0/operstate | grep 'up';then
    echo "TEST PASS"
else
    echo "TEST FAIL"
fiBug detail logs:
TINFO:ENET  up and down test 391 times
[  850.471205] Qualcomm Atheros AR8031/AR8033 30be0000.ethernet-1:00: attached PHY driver (mii_bus:phy_addr=30be0000.ethernet-1:00, irq=POLL)
[  853.535318] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[  853.541694] fec 30be0000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[  870.590531] page_pool_release_retry() stalled pool shutdown 199 inflight 60 sec
[  931.006557] page_pool_release_retry() stalled pool shutdown 199 inflight 120 sec
TINFO:ENET  up and down test 392 times
[  991.426544] page_pool_release_retry() stalled pool shutdown 192 inflight 181 sec
[ 1051.838531] page_pool_release_retry() stalled pool shutdown 170 inflight 241 sec
[ 1093.751217] Qualcomm Atheros AR8031/AR8033 30be0000.ethernet-1:00: attached PHY driver (mii_bus:phy_addr=30be0000.ethernet-1:00, irq=POLL)
[ 1096.446520] page_pool_release_retry() stalled pool shutdown 308 inflight 60 sec
[ 1096.831245] fec 30be0000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[ 1096.839092] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 1112.254526] page_pool_release_retry() stalled pool shutdown 103 inflight 302 sec
[ 1156.862533] page_pool_release_retry() stalled pool shutdown 308 inflight 120 sec
[ 1172.674516] page_pool_release_retry() stalled pool shutdown 103 inflight 362 sec
[ 1217.278532] page_pool_release_retry() stalled pool shutdown 308 inflight 181 sec
TINFO:ENET  up and down test 393 times
[ 1233.086535] page_pool_release_retry() stalled pool shutdown 103 inflight 422 sec
[ 1277.698513] page_pool_release_retry() stalled pool shutdown 308 inflight 241 sec
[ 1293.502525] page_pool_release_retry() stalled pool shutdown 86 inflight 483 sec
[ 1338.110518] page_pool_release_retry() stalled pool shutdown 308 inflight 302 sec
[ 1353.918540] page_pool_release_retry() stalled pool shutdown 32 inflight 543 sec
[ 1361.179205] Qualcomm Atheros AR8031/AR8033 30be0000.ethernet-1:00: attached PHY driver (mii_bus:phy_addr=30be0000.ethernet-1:00, irq=POLL)
[ 1364.255298] fec 30be0000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[ 1364.263189] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 1371.998532] page_pool_release_retry() stalled pool shutdown 310 inflight 60 sec
[ 1398.530542] page_pool_release_retry() stalled pool shutdown 308 inflight 362 sec
[ 1414.334539] page_pool_release_retry() stalled pool shutdown 16 inflight 604 sec
[ 1432.414520] page_pool_release_retry() stalled pool shutdown 310 inflight 120 sec
[ 1458.942523] page_pool_release_retry() stalled pool shutdown 308 inflight 422 sec
[ 1474.750521] page_pool_release_retry() stalled pool shutdown 16 inflight 664 sec
TINFO:ENET  up and down test 394 times
[ 1492.8305
---truncated---
CVSS v3.1: 5.5