[lwip-users] Memory error on DHCP retry

[rsch]

When setting up my STM32H7 with LwIP 2.1.2, FreeRTOS 10.2.0. I try to start
my device as a DHCP client.

The first try I see a DHCP Discover packet I Wireshark. After a second the
time-out kicks in and the device will start a retry. This will result in a
hardfault error.

So far I have narrowed it down to the LWIP function: dhcp_create_msg in
dhcp.c. The values dhcp->xid and p_out->next share the same address

First try:
&(dhcp->xid) = 0x20003DB8
&(p_out->next) = 0x20003DF4

Retry:
&(dhcp->xid) = 0x20003DB8
&(p_out->next) = 0x20003DB8

When the new xid is set this will automatically set the next pointer, in the
lowlevel_output following loop contains:
for(q = p; q != NULL; q = q->next)


The p_out->next (dhcp->xid) won't be NULL and will try to read the data
causing a hardfaulterror
Is there something I am missing?



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