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Nicolas Iooss
9547b609b9
While debugging issues on Linux systems using clang CFI (Control Flow Integrity, `CONFIG_CFI_CLANG`), it appeared to me that `chipsec_lookup_name` could be simplified. - Instead of using `set_fs(KERNEL_DS);` to invoke read operations, `kernel_read` can directly be used. This function existed since at least Linux 2.4.0 (https://elixir.bootlin.com/linux/2.4.0/source/fs/exec.c#L368) so there should not be compatibility issues. - Instead of allocating a 128-byte buffer with `kmalloc`, use a stack buffer. While at it, fix a buffer overflow issue on systems with large symbol names such as ones using clang's CFI: some lines were 142 characters long. - Instead of matching anything on the line of `/proc/kallsyms` with `strstr`, only do prefix-matching on the start of the symbol name. This involves counting spaces in the line, in order to extract the name as the 3rd item. - Last but not least, show a clear error message if the symbol is not found in /proc/kallsyms. This helps debugging issues. While at it, add a comment which explains why reading `/proc/kallsyms` does not work with Linux 5.10.