BUG/MEDIUM: mux-h2: do not try to free an unallocated h2s->sd

In h2s_close() we may dereference h2s->sd to get the sc, but this
function may be called on allocation error paths, so we must check
for this specific condition. Let's also update the comment to make
it explicitly permitted.

This needs to be backported to 2.6.
1 file changed