GDB: Attempt to dereference generic pointer

Question

How can I make GDB do extra dereferences in a printing function like x/s?

When I try explicit dereferences in x/ I get the error \"Attempt to d

Answer 1

The solution is to cast the pointers before dereferencing them.

For example, picking up where we left off above:

(gdb) x/s **((char ***) (0xc + $ebp))
0xbfffedc8:  "/var/tmp/SO-attempt-to-dereference-generic-pointer/example"
(gdb) x/s *(*((char ***) (0xc + $ebp)) + 1)
0xbfffee03:  "first"
(gdb) x/s *(*((char ***) (0xc + $ebp)) + 2)
0xbfffee09:  "second"

Note that the stack address 0xc + $ebp is itself a pointer to the contents of that stack location, and so we need char *** and not char **.