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charset="utf-8" With upstream kernel booted on a PowerNV system with OpenCAPI device, below crash is observed: [ 1.568588] PowerPC PowerNV PCI Hotplug Driver version: 0.1 [ 1.569722] BUG: Kernel NULL pointer dereference at 0x00000074 [ 1.569811] Faulting instruction address: 0xc000000000b75fd0 [ 1.569890] Oops: Kernel access of bad area, sig: 11 [#1] [ 1.569963] LE PAGE_SIZE=3D64K MMU=3DHash SMP NR_CPUS=3D2048 NUMA P= owerNV [ 1.570037] Modules linked in: [ 1.570099] CPU: 250 UID: 0 PID: 1 Comm: swapper/248 Not tainted 7.1= .0-rc4+ #1 PREEMPTLAZY [ 1.570207] Hardware name: 9105-22A Power11 (raw) 0x820200 opal:v7.1= -142-gbbc276524497 PowerNV [ 1.570325] NIP: c000000000b75fd0 LR: c000000000b75fbc CTR: 0000000= 03008a65c [ 1.570411] REGS: c000c0000688f6f0 TRAP: 0380 Not tainted (7.1.0-= rc4+) [ 1.570494] MSR: 9000000000009033 CR: 28= 000284 XER: 20040000 [ 1.570636] CFAR: c00000000019f9e8 IRQMASK: 0 ... [ 1.571492] NIP [c000000000b75fd0] pnv_php_get_adapter_state+0x60/0x= 154 [ 1.571604] LR [c000000000b75fbc] pnv_php_get_adapter_state+0x4c/0x1= 54 [ 1.571690] Call Trace: [ 1.571725] [c000c0000688f990] [c000000000b75fbc] pnv_php_get_adapte= r_state+0x4c/0x154 (unreliable) [ 1.571783] [c000c0000688fa20] [c000000000b78bd0] pnv_php_enable+0x9= 4/0x378 [ 1.571951] [c000c0000688fac0] [c000000000b7912c] pnv_php_register_o= ne.isra.0+0x11c/0x1e0 [ 1.572077] [c000c0000688fb00] [c000000002091318] pnv_php_init+0x168= /0x1b0 [ 1.572111] [c000c0000688fb80] [c00000000001103c] do_one_initcall+0x= 5c/0x450 [ 1.572162] [c000c0000688fc70] [c000000002006abc] do_initcalls+0x15c= /0x29c [ 1.572283] [c000c0000688fd30] [c000000002006ec4] kernel_init_freeab= le+0x224/0x3e0 [ 1.572484] [c000c0000688fde0] [c000000000011578] kernel_init+0x30/0= x268 [ 1.572562] [c000c0000688fe50] [c00000000000debc] ret_from_kernel_us= er_thread+0x14/0x1c [ 1.572667] ---- interrupt: 0 at 0x0 [ 1.572720] Code: 38810065 e90d0c78 f9010068 39000000 99210065 e8630= 020 4b6299c9 60000000 2c030000 418000ac e87f0058 89410065 552906= 36 2c090060 41820044 This NULL pointer dereference happens due to the call to 'pci_pcie_type(php_slot->pdev)' without checking if php_slot->pdev is NULL. This occurs for hotplug slots on root buses where bus->self =3D=3D NULL, such as OpenCAPI PHB direct slots. An added debug print (not part of this patch) confirmed it was opencapi: [ 1.617227] pnv_php: slot 'OPENCAPI-0009' has NULL pdev (bus 0009:00= , parent=3DNO (root bus)) [ 1.617308] pnv_php: slot 'OPENCAPI-0009' dn->full_name=3D'pciex@603= a000000000', compatible=3D'ibm,power10-pau-opencapi-pciex' Add a NULL check for this. Cc: stable@vger.kernel.org Fixes: 80f9fc236279 ("PCI: pnv_php: Work around switches with broken presen= ce detection") Signed-off-by: Aditya Gupta --- drivers/pci/hotplug/pnv_php.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c index ff92a5c301b8..21ce7ead9e19 100644 --- a/drivers/pci/hotplug/pnv_php.c +++ b/drivers/pci/hotplug/pnv_php.c @@ -414,7 +414,8 @@ static int pnv_php_get_adapter_state(struct hotplug_slo= t *slot, u8 *state) */ ret =3D pnv_pci_get_presence_state(php_slot->id, &presence); if (ret >=3D 0) { - if (pci_pcie_type(php_slot->pdev) =3D=3D PCI_EXP_TYPE_DOWNSTREAM && + if (php_slot->pdev && + pci_pcie_type(php_slot->pdev) =3D=3D PCI_EXP_TYPE_DOWNSTREAM && presence =3D=3D OPAL_PCI_SLOT_EMPTY) { /* * Similar to pciehp_hpc, check whether the Link Active --=20 2.54.0