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SubjectRe: [PATCH] kallsyms: don't leak address when printing symbol
On Thu,  9 Nov 2017 12:50:29 +1100
"Tobin C. Harding" <me@tobin.cc> wrote:

> Currently if a pointer is printed using %p[ssB] and the symbol is not
> found (kallsyms_lookup() fails) then we print the actual address. This
> leaks kernel addresses. We should instead print something _safe_.
>
> Print "<no-symbol>" instead of kernel address.

Ug, ftrace requires this to work as is, as it uses it to print some
addresses that may or may not be a symbol.

If anything, can this return a success or failure if it were to find a
symbol or not, and then something like ftrace could decide to use %x if
it does not.

And yes, ftrace leaks kernel addresses all over the place, that's just
the nature of tracing the kernel.

-- Steve


>
> Signed-off-by: Tobin C. Harding <me@tobin.cc>
> ---
> kernel/kallsyms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index 127e7cfafa55..182e7592be9c 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -390,7 +390,7 @@ static int __sprint_symbol(char *buffer, unsigned long address,
> address += symbol_offset;
> name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
> if (!name)
> - return sprintf(buffer, "0x%lx", address - symbol_offset);
> + return sprintf(buffer, "<no-symbol>");
>
> if (name != buffer)
> strcpy(buffer, name);

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