- Removed target alias from the EXPORT_MAP in targets.py as it didn't work
- Added copies of the LPC4088 target exporters
- Fixed flag issue in the gcc toolchain
- Changed defines in eth USBDevice, rpt and rtos to handle
TARGET_LPC4088_DM
tcp_write() would incorrectly byte swap the checksum 1 too many times
when concatenating a pbuf to an existing TCP segment if the number of
bytes in the concatenated data was odd. I hit this issue when I tried
to reproduce a lost segment issue reported by a mbed user in this forum
thread: http://mbed.org/forum/mbed/topic/4354/?page=2#comment-22657
After making my previous commit to completely disable LWIP_ASSERT
macro invocations, I ended up with a warning in pbuf.c where an
err variable was set but only checked for success in an assert. I
added a "(void)err;" reference to silence this warning.
The code in netif_set_ipaddr would read the memory pointed to by its
ipaddr parameter, even if it was NULL on this line:
if ((ip_addr_cmp(ipaddr, &(netif->ip_addr))) == 0) {
On the Cortex-M3, it is typically OK to read from address 0 so this
code will actually compare the reset stack pointer value to the
current value in netif->ip_addr.
Later in the code, this same pointer will be used for a second read:
ip_addr_set(&(netif->ip_addr), ipaddr);
The ip_addr_set call will first check to see if the ipaddr is NULL and
if so, treats it like IP_ADDR_ANY (4 bytes of 0).
/** Safely copy one IP address to another (src may be NULL) */
#define ip_addr_set(dest, src) ((dest)->addr = \
((src) == NULL ? 0 : \
(src)->addr))
The issue here is that when GCC optimizes this code, it assumes that
the first dereference of ipaddr would have thrown an invalid memory
access exception and execution would never make it to this second
dereference. Therefore it optimizes out the NULL check in ip_addr_set.
The -fno-delete-null-pointer-checks will disable this optimization and
is a good thing to use with GCC in general on Cortex-M parts. I will
let the mbed guys make that change to their build system.
I have however corrected the code so that the intent of how to handle a
NULL ipaddr is more obvious and gets rid of the potential NULL
dereference.
By the way, this bug caused connect() to fail in obtaining an
address from DHCP. If I recall correctly from when I first debugged
this issue (late last year), I actually saw the initial value of the
stack pointer being used in the DHCP request as an IP address which
caused it to be rejected.
The first was a potential out of range index read in dhcp_handle_ack().
The (n < DNS_MAX_SERVERS) check should occur first. There is also a
documented lwIP bug for this issue here:
http://savannah.nongnu.org/bugs/?36170
In dhcp_bind() there is no need to perform the NULL check in
ip_addr_isany() for &gw_addr. Just check (gw_addr.addr == IPADDR_ANY)
instead.
I refactored the chaddr[] copy in dhcp_create_msg() to first copy all
of the valid bytes in hwaddr and then pad the rest of the bytes with 0.
Before it used to check on every destination byte if it should copy or
pad. GCC originally complained about an index out of range read from
the hwaddr[] array even though it was protected by a conditional
operator. The refactor makes the intent a bit clearer and saves the
extra comparison per loop iteration. It also stops GCC from
complaining :)
GCC will issue a warning when the ip_addr_isany() macro is used on
a pointer which can never be NULL since the macros NULL check will
always be false:
#define ip_addr_isany(addr1) ((addr1) == NULL || \
(addr1)->addr == IPADDR_ANY)
In these cases, it is probably clearer to just perform the
x.addr == IPADDR_ANY check inline.
Yihui Xiong
Anders Lindvall
Masao Hamanaka
Bogdan Marinescu
mazgch
Adam Green
Andreas Rebert
Emilio Monti