Re: [lwip-users] [LwIP 1.4.1] Ping length of 92 bytes via PPP crashes LwIP core/pbuf.c

[Marco Jakobs]

I wonder if that allocate is correct...

This is the pbuf debug output of the crashing 92 bytes ping via PPP:

pbuf_alloc(length=0)
pbuf_alloc: allocated pbuf 0021a5cc
pbuf_alloc(length=0) == 0021a5cc
pbuf_alloc(length=0)
pbuf_alloc: allocated pbuf 0021a53c
pbuf_alloc(length=0) == 0021a53c
pbuf_header: old 0021a5dc new 0021a5e4 (-8)
pbuf_header: old 0021a5e4 new 0021a5f8 (-20)
pbuf_header: old 0021a5f8 new 0021a5e4 (20)
pbuf_header: old 0021a5e4 new 0021a5f8 (-20)
pbuf_header: failed as 0021a5d4 < 0021a5dc (not enough space for new header 
size)
pbuf_header: old 0021a5f8 new 0021a5e4 (20)
pbuf_alloc(length=120)
pbuf_alloc(length=120) == 00213b78
pbuf_copy(00213b78, 0021a5cc)
15.05.17 12:03:41 ASSERT: 
C:/Projekte/TMO-100/Libraries/lwIP/src/core/pbuf.c:888:p_to != NULL

and that's the same size over Ethernet:

pbuf_alloc(length=134)
pbuf_alloc: allocated pbuf 00219e7c
pbuf_alloc(length=134) == 00219e7c
pbuf_header: old 00219e8c new 00219e9a (-14)
pbuf_header: old 00219e9a new 00219eae (-20)
pbuf_header: old 00219eae new 00219e9a (20)
pbuf_header: old 00219e9a new 00219eae (-20)
pbuf_header: failed as 00219e8a < 00219e8c (not enough space for new header 
size)
pbuf_header: old 00219eae new 00219e9a (20)
pbuf_alloc(length=120)
pbuf_alloc(length=120) == 00213b78
pbuf_copy(00213b78, 00219e7c)
pbuf_copy: end of chain reached.
pbuf_header: old 00213b98 new 00213bac (-20)
pbuf_free(00219e7c)
...

The very first allocate is different (length=0 via PPP, length =134 via 
Ethernet).

On the other side, it's the same with a working ping of one byte more over PPP:

pbuf_alloc(length=0)
pbuf_alloc: allocated pbuf 0021a5cc
pbuf_alloc(length=0) == 0021a5cc
pbuf_alloc(length=0)
pbuf_alloc: allocated pbuf 0021a53c
pbuf_alloc(length=0) == 0021a53c
pbuf_header: old 0021a5dc new 0021a5e4 (-8)
pbuf_header: old 0021a5e4 new 0021a5f8 (-20)
pbuf_header: old 0021a5f8 new 0021a5e4 (20)
pbuf_header: old 0021a5e4 new 0021a5f8 (-20)
pbuf_header: failed as 0021a5d4 < 0021a5dc (not enough space for new header 
size)
pbuf_header: old 0021a5f8 new 0021a5e4 (20)
pbuf_alloc(length=121)
pbuf_alloc(length=121) == 00213b78
pbuf_copy(00213b78, 0021a5cc)
pbuf_copy: end of chain reached.
pbuf_header: old 00213b98 new 00213bac (-20)
pbuf_free(0021a5cc)

The first allocate is also length=0 here, but the pbuf_copy does not crash.

Is there a bell ringing?