Re: [lwip-users] pbuf_realloc in ip.c problem

[Martin Velek]

Hi Simon,

thank you for links. There was a misunderstanding. I can see that in
case of MEM_LIBC_MALLOC I should not use my realloc function or do
nothing if defined.

Regards,
Martin

2009/9/1 Simon Goldschmidt <address@hidden>:
> This was bug 27105, fixed in 1.3.1RC3 (was still included in RC1 and RC2).
>
> Link to the bug:
> http://cvs.savannah.gnu.org/viewvc/lwip/src/include/lwip/mem.h?revision=1.23&root=lwip&view=markup
>
> This has nothing to do with ip.c or pbuf.c. Please check your mem.h file 
> against the file in this link (which is the current and 1.3.1 version):
>
> http://cvs.savannah.gnu.org/viewvc/lwip/src/include/lwip/mem.h?revision=1.23&root=lwip&view=markup
>
> Especially these lines, which fix the bug:
>
>>>>
> #ifndef mem_realloc
> static void *mem_realloc(void *mem, mem_size_t size)
> {
>  LWIP_UNUSED_ARG(size);
>  return mem;
> }
> #endif
> <<<
>
> they were like this before:
>
>>>>
> #ifndef mem_realloc
> #define mem_realloc realloc
> #endif
> <<<
>
> I just checked the download link you gave and memp.h is fixed in the zip. 
> Please re-check the version you are using is really 1.3.1 stable, not an RC.
>
> You can either upgrade or change the memp.h file manually if upgrading is not 
> an option.
>
> Simon
>
>
>
>> Hi,
>>
>> I am using
>> http://download.savannah.gnu.org/releases-noredirect/lwip/lwip-1.3.1.zip
>>
>> md5
>> af8c4bf938e3ca48af3d54e29d57ab54 *ip.c
>> 1a1ec514a862fb1d931f4eb4c236cb21 *pbuf.c
>>
>> Martin
>>
>> 2009/9/1 Simon Goldschmidt <address@hidden>:
>> > Which version of lwIP are you using? This was a bug in 1.3.0 that has
>> been fixed in 1.3.1, if I remember correctly. Try upgrading to the latest
>> version to fix this.
>> >
>> > Simon
>> >
>> >
>> > -------- Original-Nachricht --------
>> >> Datum: Tue, 1 Sep 2009 09:44:09 +0200
>> >> Von: Martin Velek <address@hidden>
>> >> An: address@hidden
>> >> Betreff: [lwip-users] pbuf_realloc in ip.c problem
>> >
>> >> Hello,
>> >>
>> >> I am using lwip 1.3.1 with FreeRTOS and LM3S9B92. Because there is a
>> >> memory manager in the OS I have defined
>> >> #define MEM_LIBC_MALLOC                 1
>> >> #define MEMP_MEM_MALLOC                 1
>> >> #define MEM_USE_POOLS                   0
>> >> with bget implementation of memory manager. All incomming packets are
>> >> PBUF_RAM.
>> >>
>> >> The lwip running fine until a tcp packet to port 80 is received(http
>> >> server by netconn). The lwip will cause a invalid memory  access.
>> >>
>> >> During debuging I have discovered that in file ip.c is called
>> >> pbuf_realloc(p, iphdr_len) and inside this function is called
>> >> mem_realloc(brel). Unfortunately bget reallocate memory by creating a
>> >> new space and than will free the old memory.
>> >> However this new memory is "lost" because the new pointer is not
>> >> stored. (q = mem_realloc(q, (u8_t *)q->payload - (u8_t *)q +
>> >> rem_len);) and q is not stored back to "p".
>> >> So, p is still pointing to the deallocated memory.
>> >> I have thought that the bget implementation is wrong but the standard
>> >> C's realloc returns:
>> >> "A pointer to the reallocated memory block, which may be either the
>> >> same as the ptr argument or a new location.
>> >> The type of this pointer is void*, which can be cast to the desired
>> >> type of data pointer in order to be dereferenceable.
>> >> If the function failed to allocate the requested block of memory, a
>> >> NULL pointer is returned."
>> >>
>> >> Have anyone next similar problem?
>> >>
>> >> Thank you for your reply.
>> >>
>> >> Regards,
>> >> Martin Velek
>> >>
>> >>
>> >> _______________________________________________
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>> >
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