From: Tong Zhang <ztong0001@gmail.com> [ Upstream commit a9f81244d2e33e6dfcef120fefd30c96b3f7cdb0 ] setup_fritz() in avmfritz.c might fail with -EIO and in this case the isac.type and isac.write_reg is not initialized and remains 0(NULL). A subsequent call to isac_release() will dereference isac->write_reg and crash. [ 1.737444] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 1.737809] #PF: supervisor instruction fetch in kernel mode [ 1.738106] #PF: error_code(0x0010) - not-present page [ 1.738378] PGD 0 P4D 0 [ 1.738515] Oops: 0010 [#1] SMP NOPTI [ 1.738711] CPU: 0 PID: 180 Comm: systemd-udevd Not tainted 5.12.0-rc2+ #78 [ 1.739077] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-p rebuilt.qemu.org 04/01/2014 [ 1.739664] RIP: 0010:0x0 [ 1.739807] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. [ 1.740200] RSP: 0018:ffffc9000027ba10 EFLAGS: 00010202 [ 1.740478] RAX: 0000000000000000 RBX: ffff888102f41840 RCX: 0000000000000027 [ 1.740853] RDX: 00000000000000ff RSI: 0000000000000020 RDI: ffff888102f41800 [ 1.741226] RBP: ffffc9000027ba20 R08: ffff88817bc18440 R09: ffffc9000027b808 [ 1.741600] R10: 0000000000000001 R11: 0000000000000001 R12: ffff888102f41840 [ 1.741976] R13: 00000000fffffffb R14: ffff888102f41800 R15: ffff8881008b0000 [ 1.742351] FS: 00007fda3a38a8c0(0000) GS:ffff88817bc00000(0000) knlGS:0000000000000000 [ 1.742774] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.743076] CR2: ffffffffffffffd6 CR3: 00000001021ec000 CR4: 00000000000006f0 [ 1.743452] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1.743828] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 1.744206] Call Trace: [ 1.744339] isac_release+0xcc/0xe0 [mISDNipac] [ 1.744582] fritzpci_probe.cold+0x282/0x739 [avmfritz] [ 1.744861] local_pci_probe+0x48/0x80 [ 1.745063] pci_device_probe+0x10f/0x1c0 [ 1.745278] really_probe+0xfb/0x420 [ 1.745471] driver_probe_device+0xe9/0x160 [ 1.745693] device_driver_attach+0x5d/0x70 [ 1.745917] __driver_attach+0x8f/0x150 [ 1.746123] ? device_driver_attach+0x70/0x70 [ 1.746354] bus_for_each_dev+0x7e/0xc0 [ 1.746560] driver_attach+0x1e/0x20 [ 1.746751] bus_add_driver+0x152/0x1f0 [ 1.746957] driver_register+0x74/0xd0 [ 1.747157] ? 0xffffffffc00d8000 [ 1.747334] __pci_register_driver+0x54/0x60 [ 1.747562] AVM_init+0x36/0x1000 [avmfritz] [ 1.747791] do_one_initcall+0x48/0x1d0 [ 1.747997] ? __cond_resched+0x19/0x30 [ 1.748206] ? kmem_cache_alloc_trace+0x390/0x440 [ 1.748458] ? do_init_module+0x28/0x250 [ 1.748669] do_init_module+0x62/0x250 [ 1.748870] load_module+0x23ee/0x26a0 [ 1.749073] __do_sys_finit_module+0xc2/0x120 [ 1.749307] ? __do_sys_finit_module+0xc2/0x120 [ 1.749549] __x64_sys_finit_module+0x1a/0x20 [ 1.749782] do_syscall_64+0x38/0x90 Signed-off-by: Tong Zhang <ztong0001@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/isdn/hardware/mISDN/mISDNipac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/isdn/hardware/mISDN/mISDNipac.c b/drivers/isdn/hardware/mISDN/mISDNipac.c index 4d78f870435ec..71e635d6c64a2 100644 --- a/drivers/isdn/hardware/mISDN/mISDNipac.c +++ b/drivers/isdn/hardware/mISDN/mISDNipac.c @@ -710,7 +710,7 @@ isac_release(struct isac_hw *isac) { if (isac->type & IPAC_TYPE_ISACX) WriteISAC(isac, ISACX_MASK, 0xff); - else + else if (isac->type != 0) WriteISAC(isac, ISAC_MASK, 0xff); if (isac->dch.timer.function != NULL) { del_timer(&isac->dch.timer); -- 2.25.1