On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@xxxxxxxxxxxx wrote: > Possible approaches are: > 1. stop printing kernel addresses > 2. print with %pK, > 3. print with %px. No. The point of obscuring kernel addresses is that if the attacker manages to find a way to get the kernel to spit out some debug messages that we shouldn't leak all this extra information. > 4. do nothing 5. Find something more useful to print. > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____) ... you don't have any randomness on your platform? > INFO: Object 0x(____ptrval____) @offset=1408 fp=0x(____ptrval____) > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone (____ptrval____): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object (____ptrval____): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 > Redzone (____ptrval____): bb bb bb bb bb bb bb bb > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding (____ptrval____): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > ... > FIX kmalloc-128: Object at 0x(____ptrval____) not freed But if you have randomness, at least some of these "pointers" are valuable because you can compare them against "pointers" printed by other parts of the kernel. > After this patch: > > INFO: Slab 0xffffffbf00f57000 objects=25 used=23 fp=0xffffffc03d5c3500 > INFO: Object 0xffffffc03d5c3500 @offset=13568 fp=0xffffffc03d5c0800 > Redzone 00000000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000010: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000020: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000030: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000040: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000050: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000060: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Redzone 00000070: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb > Object 00000000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000040: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000050: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000060: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b > Object 00000070: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 > Redzone 00000000: bb bb bb bb bb bb bb bb > Padding 00000000: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000010: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000020: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > Padding 00000030: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a > ... > FIX kmalloc-128: Object at 0xffffffc03d5c3500 not freed It looks prettier, but I'm not convinced it's more useful. Unless your platform lacks randomness ...
