On Thu, Apr 11, 2024 at 02:52:27PM +0800, Sam Sun wrote: > Dear developers and maintainers, > > We encountered a general protection fault in function disable_store. > It is tested against the latest upstream linux (tag 6.9-rc3). C repro > and kernel config are attached to this email. Kernel crash log is > listed below. > ``` > general protection fault, probably for non-canonical address > 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > CPU: 1 PID: 9459 Comm: syz-executor414 Not tainted 6.7.0-rc7 #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 > RIP: 0010:disable_store+0xd0/0x3d0 drivers/usb/core/port.c:88 > Code: 02 00 00 4c 8b 75 40 4d 8d be 58 ff ff ff 4c 89 ff e8 a4 20 fa > ff 48 89 c2 48 89 c5 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c > 02 00 0f 85 b0 02 00 00 48 8b 45 00 48 8d bb 34 05 00 00 48 > RSP: 0018:ffffc90006e3fc08 EFLAGS: 00010246 > RAX: dffffc0000000000 RBX: ffff88801d4d4008 RCX: ffffffff86706be8 > RDX: 0000000000000000 RSI: ffffffff86706c4d RDI: 0000000000000005 > RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff92000dc7f85 > R13: ffff88810f4bfb18 R14: ffff88801d4d10a8 R15: ffff88801d4d1000 > FS: 00007fa0af71b640(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fa0af71a4b8 CR3: 0000000022f5f000 CR4: 0000000000750ef0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > PKRU: 55555554 > ---------------- > Code disassembly (best guess): > 0: 02 00 add (%rax),%al > 2: 00 4c 8b 75 add %cl,0x75(%rbx,%rcx,4) > 6: 40 rex > 7: 4d 8d be 58 ff ff ff lea -0xa8(%r14),%r15 > e: 4c 89 ff mov %r15,%rdi > 11: e8 a4 20 fa ff call 0xfffa20ba > 16: 48 89 c2 mov %rax,%rdx > 19: 48 89 c5 mov %rax,%rbp > 1c: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax > 23: fc ff df > 26: 48 c1 ea 03 shr $0x3,%rdx > * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- > trapping instruction > 2e: 0f 85 b0 02 00 00 jne 0x2e4 > 34: 48 8b 45 00 mov 0x0(%rbp),%rax > 38: 48 8d bb 34 05 00 00 lea 0x534(%rbx),%rdi > 3f: 48 rex.W > ``` > We analyzed the root cause of this bug. When calling disable_store() > in drivers/usb/core/port.c, if function authorized_store() is calling > usb_deauthorized_device() concurrently, the usb_interface will be > removed by usb_disable_device. However, in function disable_store, > usb_hub_to_struct_hub() would try to deref interface, causing > nullptr-deref. We also tested other functions in > drivers/usb/core/port.c. So far we haven't found a similar problem. I don't see how this explanation could be correct. disable_store() is a sysfs attribute file for the port device, so when it is called the port device structure must still be registered. The interface structure doesn't get removed until after usb_disable_device() calls device_del(), which won't return until hub_disconnect() returns, which won't happen until after the port devices are unregistered, which doesn't happen until disable_store() calls sysfs_break_active_protection(), which is after the call to usb_hub_to_struct_hub(). Can you do a little extra debugging to find out exactly which C statement causes the trap? The disassembly above indicates the trap happens during a compare against 0 inside disable_store() -- not inside usb_hub_to_struct_hub(). Can you figure out which comparison that is? Alan Stern > If you have any questions, please contact us. > > Reported by Yue Sun <samsun1006219@xxxxxxxxx> > Reported by xingwei lee <xrivendell7@xxxxxxxxx> > > Best Regards, > Yue
