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sbi_ecall_get_extensions_str() advanced offset by the nominal extension
name length without checking remaining capacity. When the caller buffer
was smaller than the concatenated extension list, offset could pass
exts_str_size, so (exts_str_size - offset) became negative and was
passed to sbi_snprintf() as a large u32, and the trailing NUL write
could step past the caller buffer.
The helper can write beyond a caller-provided destination when the
registered extension list exceeds the supplied capacity.
Mirror the guard already used by sbi_hart_get_extensions_str(): stop
appending when the next name would not fit. Add an SBIUNIT regression
that registers several extensions into a 16-byte buffer with a redzone
and verifies no out-of-bounds write.
Closes: https://github.com/riscv-software-src/opensbi/issues/416
Signed-off-by: Yudistira Putra <[email protected]>
Reviewed-by: Anup Patel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Anup Patel <[email protected]>
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