[PATCH] fix minor memory issues in vi and cpio

[Sarah Harris]

No, the write here:
while (isalnum_(*++p)) {
--> p[-1] = *p;
}

I can demonstrate my example by adding some printf's.
With the attached patch applied, the command "./busybox awk -e foo" produces this output:
argv[0]: 0x7ffec28dde2d "awk"
argv[1]: 0x7ffec28dde31 "-e"
argv[2]: 0x7ffec28dde34 "foo"
program: 0x7ffec28dde34 "foo"
write: 0x7ffec28dde33  0x00
write: 0x7ffec28dde34 f 0x66
write: 0x7ffec28dde35 o 0x6f

The first write to p[-1] is before argv[2] (i.e. before the program buffer), and overwrites the null at the end of argv[1].
This probably works, so long as argv[1] is always there to overwrite and isn't read afterward.

Kind regards,
Sarah Harris
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