RFA: Another Rust demangler recursion limit
Commit Message
Hi Jeff,
[I am sending this to your directly since you seem to be the only one
reviewing these patches].
Hot on the heels of the fix for the recursion problem in demangle_const
a binutils user has filed another PoC that exposes a problem in
demangle_path_maybe_open_generics():
https://sourceware.org/bugzilla/show_bug.cgi?id=29312#c1
I have redirected them to file a bug report with the gcc system, but in
the hopes of getting a fix in quickly I am also attaching a patch
here. It just does the obvious thing of adding a recursion counter
and limit to the function.
Cheers
Nick
Comments
On 7/1/2022 9:12 AM, Nick Clifton wrote:
> Hi Jeff,
>
> [I am sending this to your directly since you seem to be the only one
> reviewing these patches].
>
> Hot on the heels of the fix for the recursion problem in demangle_const
> a binutils user has filed another PoC that exposes a problem in
> demangle_path_maybe_open_generics():
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=29312#c1
>
> I have redirected them to file a bug report with the gcc system, but in
> the hopes of getting a fix in quickly I am also attaching a patch
> here. It just does the obvious thing of adding a recursion counter
> and limit to the function.
OK. And yes, I wish someone else was looking at this stuff. Rust isn't
really on my radar right now...
jeff
Hi Jeff,
> OK.
Thanks.
> And yes, I wish someone else was looking at this stuff. Rust isn't really on my radar right now...
I have been toying with the idea of putting myself forward as a maintainer
for the libiberty sources. I just wish that I had more free time...
Cheers
Nick
@@ -1082,6 +1082,18 @@ demangle_path_maybe_open_generics (struct rust_demangler *rdm)
if (rdm->errored)
return open;
+ if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+ {
+ ++ rdm->recursion;
+ if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
+ {
+ /* FIXME: There ought to be a way to report
+ that the recursion limit has been reached. */
+ rdm->errored = 1;
+ goto end_of_func;
+ }
+ }
+
if (eat (rdm, 'B'))
{
backref = parse_integer_62 (rdm);
@@ -1107,6 +1119,11 @@ demangle_path_maybe_open_generics (struct rust_demangler *rdm)
}
else
demangle_path (rdm, 0);
+
+ end_of_func:
+ if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+ -- rdm->recursion;
+
return open;
}