[PATCH] Fix modification of read-only string

[Marc Dionne]

On Tue, Feb 3, 2026 at 5:03 AM David Howells <dhowells at redhat.com> wrote:
>
> In cellserv_parse_address(), when parsing an IPv6 address bounded by
> "[...]", it searches the const string for the closing ']' and then modifies
> the string to end it at the ']' position.  This previously compiled fine
> because strchr() got rid of the const, however in Fedora 44 this is now
> detected by the compiler.
>
> Fix this by constructing the desired string in a stack buffer.
>
> Signed-off-by: David Howells <dhowells at redhat.com>
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2434693
> ---
>  src/lib_cellserv.c |    8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/src/lib_cellserv.c b/src/lib_cellserv.c
> index 1419532..1debec0 100644
> --- a/src/lib_cellserv.c
> +++ b/src/lib_cellserv.c
> @@ -66,13 +66,17 @@ static int cellserv_parse_address(const struct kafs_profile *child,
>         }
>
>         if (v[0] == '[') {
> -               char *p;
> +               char *p, *q;

I think you want to make 'p' a const char *.

>
>                 v++;
>                 p = strchr(v, ']');

Otherwise this generates an "assignment discards ‘const’ qualifier
from pointer target type" error.

>                 if (!p || p[1])
>                         goto invalid;
> -               p[0] = 0;
> +
> +               q = alloca(p - v + 1);
> +               memcpy(q, v, p - v);
> +               q[p - v] = 0;
> +               v = q;
>         }
>
>         if (inet_pton(AF_INET6, v, &addr->sin6.sin6_addr) == 1) {
>
>

Marc