[BusyBox] patch to login, dmesg and obscure

[Robert Griebl]

Ronny L Nilsson wrote:
>>Example:
>>old = "123" (4 bytes)
>>wrapped allocated = 3*2 + 1 = 7 bytes.
>>first initialisez only 4 bytes = "123"
>>after strcat resut is "123123" - 7 bytes.
>>Not overflow.
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> This start to be realy fun soon...  :-)  The litte prog below mimics
> password_check() behaviour and it sure craches on my machine. Howcome?
> It shouldn't if you're right.
>
> /Ronny
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> 	strcat(wrapped, wrapped);

Simple explanation:

start of strcat: wrapped = "0123456789\0"
after first iteration: wrapped = "01234567890"

No terminating '\0' byte anymore and since wrapped is also the cat'ed
string, characters are append until a \0 is hit in the following memory
areas (if there _are_ any mapped areas beyond that string)

cu
Robert