Messages in this thread Patch in this message | | | From | Luis Chamberlain <> | Subject | [PATCH] cxl/acpi: fix null dereference on probe for missing ACPI_COMPANION() | Date | Thu, 8 Dec 2022 22:29:19 -0800 |
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Simply loading cxl_test ends up triggering a null pointer dereference on next-20221207, and it happens because the fetched ACPI_COMPANION() can end up not correct / missing. As with other code which uses ACPI_COMPANION() (drivers/acpi/device_pm.c comes to mind) be defensive over the assumption the companion is always present and bail right away.
This can be easily reproduced with kdevops [0] with linux next-20221207 [1] and cxl enabled workflows:
make menuconfig # enable cxl and linux-next make # sets up variables, builds qemu from source make linux # builds and install next-20221207 make cxl # installs cxl tool make cxl-test-probe # loads cxl_test
The oops:
# modprobe cxl_test No TPM handle discovered. failed to open file /etc/ndctl/keys/nvdimm-master.blob: No such file or directory
[0] https://github.com/linux-kdevops/kdevops [1] https://github.com/linux-kdevops/kdevops/blob/master/playbooks/roles/bootlinux/templates/config-next-20221207
cxl_mock: loading out-of-tree module taints kernel. cxl_mock: loading test module taints kernel. cxl_mem mem0: at cxl_root_port.0 no parent for dport: platform cxl_mem mem1: at cxl_root_port.1 no parent for dport: platform cxl_mem mem2: at cxl_root_port.2 no parent for dport: platform cxl_mem mem3: at cxl_root_port.3 no parent for dport: platform cxl_mem mem4: at cxl_root_port.0 no parent for dport: platform cxl_mem mem5: at cxl_root_port.1 no parent for dport: platform cxl_mem mem6: at cxl_root_port.2 no parent for dport: platform cxl_mem mem7: at cxl_root_port.3 no parent for dport: platform cxl_mem mem8: at cxl_root_port.4 no parent for dport: platform cxl_mem mem9: at cxl_root_port.4 no parent for dport: platform cxl_mem mem10: CXL port topology not found BUG: kernel NULL pointer dereference, address: 00000000000002c0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 4 PID: 1644 Comm: systemd-udevd Kdump: loaded Tainted: G O N 6.1.0-rc8-next-20221207 #5 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.1-0-g3208b098f51a-prebuilt.qemu.org 04/01/2014 RIP: 0010:cxl_acpi_probe+0xeb/0x2f0 [cxl_acpi] Code: ff ff ff 48 c7 40 08 ff ff ff ff 48 c7 40 18 00 02 00 00 e8 57 29 fd ff 49 89 c7 41 89 c4 48 3d 00 f0 ff ff 0f 87 73 ff ff ff <49> 8b bd c0 02 00 00 48 c7 c1 c0 64 e4 c0 48 89 c2 31 f6 e8 bd f1 RSP: 0018:ffffbe6d008b7c30 EFLAGS: 00010287 RAX: ffff97a7c6e01000 RBX: ffff97a7c51fd810 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000282 RDI: 00000000ffffffff RBP: 0000000000000000 R08: ffff97a7c51fdaa8 R09: 0000000000000010 R10: 0000000000000002 R11: 00000000000013c7 R12: 00000000c6e01000 R13: 0000000000000000 R14: ffff97a7d9c653a8 R15: ffff97a7c6e01000 FS: 00007f34b038ed00(0000) GS:ffff97a83bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000002c0 CR3: 0000000102f7e005 CR4: 0000000000770ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? kernfs_create_link+0x5d/0xa0 platform_probe+0x41/0x90 really_probe+0xdb/0x380 ? pm_runtime_barrier+0x50/0x90 __driver_probe_device+0x78/0x170 driver_probe_device+0x1f/0x90 __driver_attach+0xce/0x1c0 ? __pfx___driver_attach+0x10/0x10 bus_for_each_dev+0x73/0xc0 bus_add_driver+0x1ae/0x200 driver_register+0x89/0xe0 ? __pfx_init_module+0x10/0x10 [cxl_acpi] do_one_initcall+0x43/0x220 ? kmalloc_trace+0x26/0x90 do_init_module+0x4a/0x1f0 __do_sys_init_module+0x17f/0x1b0 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f34b061baaa Code: 48 8b 0d 59 83 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 af 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 26 83 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007fff6a198408 EFLAGS: 00000246 ORIG_RAX: 00000000000000af RAX: ffffffffffffffda RBX: 00005635afc7e5e0 RCX: 00007f34b061baaa RDX: 00007f34b07a5efd RSI: 0000000000060a29 RDI: 00005635afdd6510 RBP: 00007f34b07a5efd R08: 000000000001f5b3 R09: 0000000000000000 R10: 000000000000eb81 R11: 0000000000000246 R12: 00005635afdd6510 R13: 0000000000000000 R14: 00005635afca6f40 R15: 00005635af874e50 </TASK> Modules linked in: cxl_acpi(+) cxl_pmem cxl_mem cxl_port cxl_mock_mem(ON) cxl_test(ON) cxl_mock(ON) cxl_core libnvdimm cbc encrypted_keys kvm_intel kvm 9p netfs irqbypass crct10dif_pclmul ghash_clmulni_intel sha512_ssse3 sha512_generic aesni_intel crypto_simd cryptd cirrus drm_shmem_helper 9pnet_virtio virtio_balloon i6300esb drm_kms_helper joydev evdev button serio_raw drm configfs ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs blake2b_generic raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c crc32c_generic raid1 raid0 md_mod virtio_net net_failover virtio_blk failover psmouse virtio_pci virtio_pci_legacy_dev nvme virtio_pci_modern_dev crc32_pclmul nvme_core virtio crc32c_intel t10_pi virtio_ring crc64_rocksoft crc64
And gdb:
(gdb) l *(cxl_acpi_probe+0xeb) 0xa8b is in cxl_acpi_probe (tools/testing/cxl/../../../drivers/cxl/acpi.c:648). 643 644 root_port = devm_cxl_add_port(host, host, CXL_RESOURCE_NONE, NULL); 645 if (IS_ERR(root_port)) 646 return PTR_ERR(root_port); 647 648 rc = bus_for_each_dev(adev->dev.bus, NULL, root_port, 649 add_host_bridge_dport); 650 if (rc < 0) 651 return rc; 652
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> ---
Note: kdevops also suports now the target:
make cxl-test-meson
But that does not *at least* crash the kernel although the tests fail too... This is likely a misconfiguration of some sort, but the same kernel works fine when I enable a Type 3 memory device (also supported on kdevops via CONFIG_QEMU_ENABLE_CXL_DEMO_TOPOLOGY_1). This test was run without that enabled, so a naked cxl system.
Even if it *was* a mis-configuration, such things should not crash the kernel.
drivers/cxl/acpi.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index ad0849af42d7..cf5d1a455efc 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -633,6 +633,9 @@ static int cxl_acpi_probe(struct platform_device *pdev) struct acpi_device *adev = ACPI_COMPANION(host); struct cxl_cfmws_context ctx; + if (!adev) + return -ENODEV; + device_lock_set_class(&pdev->dev, &cxl_root_key); rc = devm_add_action_or_reset(&pdev->dev, cxl_acpi_lock_reset_class, &pdev->dev); -- 2.35.1
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