[PATCH] PCI: Fix NULL dereference in SR-IOV VF creation error path

[Shay Drory <shayd@nvidia.com>]

Add proper cleanup when virtfn setup fails to prevent NULL pointer
dereference during device removal. The kernel oops[1] occurred due to
Incorrect error handling flow when pci_setup_device() fails.

Fix it by properly cleaning up virtfn resources when pci_setup_device()
fails, instead of invoking pci_stop_and_remove_bus_device().
This prevents accessing partially initialized virtfn devices during
removal.

[1]
BUG: kernel NULL pointer dereference, address: 00000000000000d0
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP
CPU: 22 UID: 0 PID: 1151 Comm: bash Not tainted 6.13.0+ #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:device_del+0x3d/0x3d0
Call Trace:
 <TASK>
 ? __die+0x20/0x60
 ? page_fault_oops+0x150/0x3e0
 ? exc_page_fault+0x74/0x130
 ? asm_exc_page_fault+0x22/0x30
 ? device_del+0x3d/0x3d0
 pci_remove_bus_device+0x7c/0x100
 pci_iov_add_virtfn+0xfa/0x200
 sriov_enable+0x208/0x420
 mlx5_core_sriov_configure+0x6a/0x160 [mlx5_core]
 sriov_numvfs_store+0xae/0x1a0
 kernfs_fop_write_iter+0x109/0x1a0
 vfs_write+0x2c0/0x3e0
 ksys_write+0x62/0xd0
 do_syscall_64+0x4c/0x100
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: e3f30d563a38 ("PCI: Make pci_destroy_dev() concurrent safe")
CC: Keith Busch <kbusch@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Shay Drory <shayd@nvidia.com>
---
 drivers/pci/iov.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 9e4770cdd4d5..3dfcbf10e127 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -314,8 +314,11 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 		pci_read_vf_config_common(virtfn);
 
 	rc = pci_setup_device(virtfn);
-	if (rc)
+	if (rc) {
+		pci_bus_put(virtfn->bus);
+		kfree(virtfn);
 		goto failed1;
+	}
 
 	virtfn->dev.parent = dev->dev.parent;
 	virtfn->multifunction = 0;
@@ -336,14 +339,15 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 	pci_device_add(virtfn, virtfn->bus);
 	rc = pci_iov_sysfs_link(dev, virtfn, id);
 	if (rc)
-		goto failed1;
+		goto failed2;
 
 	pci_bus_add_device(virtfn);
 
 	return 0;
 
-failed1:
+failed2:
 	pci_stop_and_remove_bus_device(virtfn);
+failed1:
 	pci_dev_put(dev);
 failed0:
 	virtfn_remove_bus(dev->bus, bus);
-- 
2.38.1