Re: [PATCH 0/3] fix a couple of atm->phy_data related issues

Hi Alex,
attached is the kernel log for zatm(uPD98402) -- I also have
idt77252's log -- which is similar to this one --
I think it makes sense to drop if no one is actually using it --
- Tong

[    5.740774] BUG: KASAN: null-ptr-deref in uPD98402_start+0x5e/0x219
[uPD98402]
[    5.741179] Write of size 4 at addr 000000000000002c by task modprobe/96
[    5.741548]
[    5.741637] CPU: 0 PID: 96 Comm: modprobe Not tainted 5.12.0-rc2-dirty #71
[    5.742017] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
[    5.742635] Call Trace:
[    5.742775]  dump_stack+0x8a/0xb5
[    5.742966]  kasan_report.cold+0x10f/0x111
[    5.743197]  ? uPD98402_start+0x5e/0x219 [uPD98402]
[    5.743473]  uPD98402_start+0x5e/0x219 [uPD98402]
[    5.743739]  zatm_init_one+0x10b5/0x1311 [zatm]
[    5.743998]  ? zatm_int.cold+0x30/0x30 [zatm]
[    5.744246]  ? _raw_write_lock_irqsave+0xd0/0xd0
[    5.744507]  ? __mutex_lock_slowpath+0x10/0x10
[    5.744757]  ? _raw_spin_unlock_irqrestore+0xd/0x20
[    5.745030]  ? zatm_int.cold+0x30/0x30 [zatm]
[    5.745278]  local_pci_probe+0x6f/0xb0
[    5.745492]  pci_device_probe+0x171/0x240
[    5.745718]  ? pci_device_remove+0xe0/0xe0
[    5.745949]  ? kernfs_create_link+0xb6/0x110
[    5.746190]  ? sysfs_do_create_link_sd.isra.0+0x76/0xe0
[    5.746482]  really_probe+0x161/0x420
[    5.746691]  driver_probe_device+0x6d/0xd0
[    5.746923]  device_driver_attach+0x82/0x90
[    5.747158]  ? device_driver_attach+0x90/0x90
[    5.747402]  __driver_attach+0x60/0x100
[    5.747621]  ? device_driver_attach+0x90/0x90
[    5.747864]  bus_for_each_dev+0xe1/0x140
[    5.748075]  ? subsys_dev_iter_exit+0x10/0x10
[    5.748320]  ? klist_node_init+0x61/0x80
[    5.748542]  bus_add_driver+0x254/0x2a0
[    5.748760]  driver_register+0xd3/0x150
[    5.748977]  ? 0xffffffffc0030000
[    5.749163]  do_one_initcall+0x84/0x250
[    5.749380]  ? trace_event_raw_event_initcall_finish+0x150/0x150
[    5.749714]  ? _raw_spin_unlock_irqrestore+0xd/0x20
[    5.749987]  ? create_object+0x395/0x510
[    5.750210]  ? kasan_unpoison+0x21/0x50
[    5.750427]  do_init_module+0xf8/0x350
[    5.750640]  load_module+0x40c5/0x4410
[    5.750854]  ? module_frob_arch_sections+0x20/0x20
[    5.751123]  ? kernel_read_file+0x1cd/0x3e0
[    5.751364]  ? __do_sys_finit_module+0x108/0x170
[    5.751628]  __do_sys_finit_module+0x108/0x170
[    5.751879]  ? __ia32_sys_init_module+0x40/0x40
[    5.752126]  ? file_open_root+0x200/0x200
[    5.752353]  ? do_sys_open+0x85/0xe0
[    5.752556]  ? filp_open+0x50/0x50
[    5.752750]  ? fpregs_assert_state_consistent+0x4d/0x60
[    5.753042]  ? exit_to_user_mode_prepare+0x2f/0x130
[    5.753316]  do_syscall_64+0x33/0x40
[    5.753519]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[    5.753802] RIP: 0033:0x7ff64032dcf7
 ff c3 48 c7 c6 01 00 00 00 e9 a1
[    5.755029] RSP: 002b:00007ffd250ea358 EFLAGS: 00000246 ORIG_RAX:
0000000000000139
[    5.755449] RAX: ffffffffffffffda RBX: 0000000001093a70 RCX: 00007ff64032dcf7
[    5.755847] RDX: 0000000000000000 RSI: 00000000010929e0 RDI: 0000000000000003
[    5.756242] RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000001
[    5.756635] R10: 00007ff640391300 R11: 0000000000000246 R12: 00000000010929e0
[    5.757029] R13: 0000000000000000 R14: 0000000001092dd0 R15: 0000000000000001

On Mon, Mar 8, 2021 at 12:47 PM Alexander Duyck
[off-list ref] wrote:

On Mon, Mar 8, 2021 at 12:39 AM Tong Zhang [off-list ref] wrote:

quoted

there are two drivers(zatm and idt77252) using PRIV() (i.e. atm->phy_data)
to store private data, but the driver happens to populate wrong
pointers: atm->dev_data. which actually cause null-ptr-dereference in
following PRIV(dev). This patch series attemps to fix those two issues
along with a typo in atm struct.

Tong Zhang (3):
  atm: fix a typo in the struct description
  atm: uPD98402: fix incorrect allocation
  atm: idt77252: fix null-ptr-dereference

 drivers/atm/idt77105.c | 4 ++--
 drivers/atm/uPD98402.c | 2 +-
 include/linux/atmdev.h | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

For the 2 phys you actually seen null pointer dereferences or are your
changes based on just code review?

I ask because it seems like this code has been this way since 2005 and
in the case of uPD98402_start the code doesn't seem like it should
function the way it was as PRIV is phy_data and there being issues
seems pretty obvious since the initialization of things happens
immediately after the allocation.

I'm just wondering if it might make more sense to drop the code if it
hasn't been run in 15+ years rather than updating it?