this code and configuration shows how a weak C library can be a bullet to your foot and change memory data collaterally!
Our weak library changes x and y variables together without any error or warning, that shows we should have a very good understanding about memory and it's L/R Values!
First, we have x and y, each of which uses 1B of memory as a character.
| L Val | R Val |
|---|---|
| ... | ... |
| ------- | ------- |
| &8000 | 0x61 |
| ------- | ------- |
| &8001 | 0x62 |
| ------- | ------- |
| &8002 | 0x00 |
| &8003 | 0x00 |
| ... | ... |
After executing f() we actually assign x=0x00003B29. That affects 4B of memory, and also written on y, as you can see the C linker doesn't care!
| L Val | R Val |
|---|---|
| ... | ... |
| ------- | ------- |
| &8000 | 0x29 |
| &8001 | 0x3b |
| &8002 | 0x00 |
| &8003 | 0x00 |
| ------- | ------- |
| ... | ... |