FS#3015 - ag71xx crashes after increasing MTU #7782
Labels
flyspray
kernel
pull request/issue with Linux kernel related changes
release/19.07
pull request/issue targeted (also) for OpenWrt 19.07 release
rkreis:
Tested on openwrt-19.07.2-ath79-generic-tplink_archer-c7-v5
Steps to reproduce:
root@OpenWrt:
# ip link set eth0 mtu 500# ip link set eth0 down; ip link set eth0 uproot@OpenWrt:
root@OpenWrt:~# ip link set eth0 mtu 1500
After this, sending a large packet (ping -s 800) causes a kernel panic:
skbuff: skb_over_panic: text:802da154 len:846 put:846 head:8677e3e0 data:8677e422 tail:0x8677e770 end:0x8677e640 dev:
The problem is the rx buffer management in target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c: ag71xx_change_mtu adjusts the MTU, but doesn't adjust rx_buf_size (it's only set in ag71xx_open).
The attached patch fixes it by always using a large receive buffer. Maybe it is better to change rx_buf_size from ag71xx_change_mtu, but I don't know how to do that.
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