linux/drivers/net/ethernet/meta/fbnic
Bobby Eshleman 593dfd40a9 eth: fbnic: fix double-free of PCS on phylink creation failure
fbnic_phylink_create() stores the newly allocated PCS in fbn->pcs and
then calls phylink_create(). When phylink_create() fails, the error path
correctly destroys the PCS via xpcs_destroy_pcs(), but the caller,
fbnic_netdev_alloc(), responds by invoking fbnic_netdev_free() which
calls fbnic_phylink_destroy(). That function finds fbn->pcs non-NULL and
calls xpcs_destroy_pcs() a second time on the already-freed object,
triggering a refcount underflow use-after-free:

[   1.934973] fbnic 0000:01:00.0: Failed to create Phylink interface, err: -22
[   1.935103] ------------[ cut here ]------------
[   1.935179] refcount_t: underflow; use-after-free.
[   1.935252] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x59/0x90, CPU#0: swapper/0/1
[   1.935389] Modules linked in:
[   1.935484] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.0.0-virtme-04244-g1f5ffc672165-dirty #1 PREEMPT(lazy)
[   1.935661] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   1.935826] RIP: 0010:refcount_warn_saturate+0x59/0x90
[   1.935931] Code: 44 48 8d 3d 49 f9 a7 01 67 48 0f b9 3a e9 bf 1e 96 00 48 8d 3d 48 f9 a7 01 67 48 0f b9 3a c3 cc cc cc cc 48 8d 3d 47 f9 a7 01 <67> 48 0f b9 3a c3 cc cc cc cc 48 8d 3d 46 f9 a7 01 67 48 0f b9 3a
[   1.936274] RSP: 0000:ffffd0d440013c58 EFLAGS: 00010246
[   1.936376] RAX: 0000000000000000 RBX: ffff8f39c188c278 RCX: 000000000000002b
[   1.936524] RDX: ffff8f39c004f000 RSI: 0000000000000003 RDI: ffffffff96abab00
[   1.936692] RBP: ffff8f39c188c240 R08: ffffffff96988e88 R09: 00000000ffffdfff
[   1.936835] R10: ffffffff96878ea0 R11: 0000000000000187 R12: 0000000000000000
[   1.936970] R13: ffff8f39c0cef0c8 R14: ffff8f39c1ac01c0 R15: 0000000000000000
[   1.937114] FS:  0000000000000000(0000) GS:ffff8f3ba08b4000(0000) knlGS:0000000000000000
[   1.937273] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   1.937382] CR2: ffff8f3b3ffff000 CR3: 0000000172642001 CR4: 0000000000372ef0
[   1.937540] Call Trace:
[   1.937619]  <TASK>
[   1.937698]  xpcs_destroy_pcs+0x25/0x40
[   1.937783]  fbnic_netdev_alloc+0x1e5/0x200
[   1.937859]  fbnic_probe+0x230/0x370
[   1.937939]  local_pci_probe+0x3e/0x90
[   1.938013]  pci_device_probe+0xbb/0x1e0
[   1.938091]  ? sysfs_do_create_link_sd+0x6d/0xe0
[   1.938188]  really_probe+0xc1/0x2b0
[   1.938282]  __driver_probe_device+0x73/0x120
[   1.938371]  driver_probe_device+0x1e/0xe0
[   1.938466]  __driver_attach+0x8d/0x190
[   1.938560]  ? __pfx___driver_attach+0x10/0x10
[   1.938663]  bus_for_each_dev+0x7b/0xd0
[   1.938758]  bus_add_driver+0xe8/0x210
[   1.938854]  driver_register+0x60/0x120
[   1.938929]  ? __pfx_fbnic_init_module+0x10/0x10
[   1.939026]  fbnic_init_module+0x25/0x60
[   1.939109]  do_one_initcall+0x49/0x220
[   1.939202]  ? rdinit_setup+0x20/0x40
[   1.939304]  kernel_init_freeable+0x1b0/0x310
[   1.939449]  ? __pfx_kernel_init+0x10/0x10
[   1.939560]  kernel_init+0x1a/0x1c0
[   1.939640]  ret_from_fork+0x1ed/0x240
[   1.939730]  ? __pfx_kernel_init+0x10/0x10
[   1.939805]  ret_from_fork_asm+0x1a/0x30
[   1.939886]  </TASK>
[   1.939927] ---[ end trace 0000000000000000 ]---
[   1.940184] fbnic 0000:01:00.0: Netdev allocation failed

Instead of calling fbnic_phylink_destroy(), the prior initialization of
netdev should just be unrolled with free_netdev() and clearing
fbd->netdev.

Clearing fbd->netdev to NULL avoids UAF in init_failure_mode where
callers guard by checking !fbd->netdev, such as fbnic_mdio_read_pmd().
These callers remain active even after a failed probe, so fdb->netdev
still needs to be cleared.

Fixes: d0fe7104c7 ("fbnic: Replace use of internal PCS w/ Designware XPCS")
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260504-fbnic-pcs-fix-v2-1-de45192821d9@meta.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-07 12:34:42 +02:00
..
fbnic_csr.c eth fbnic: Add register self test 2026-03-10 13:53:53 +01:00
fbnic_csr.h fbnic: Set Relaxed Ordering PCIe TLP attributes for DMA engines 2026-03-31 16:05:19 +02:00
fbnic_debugfs.c eth: fbnic: Fix debugfs output for BDQ's with page frags 2026-03-27 20:30:23 -07:00
fbnic_devlink.c fbnic: Set Relaxed Ordering PCIe TLP attributes for DMA engines 2026-03-31 16:05:19 +02:00
fbnic_drvinfo.h
fbnic_ethtool.c eth fbnic: Add mailbox self test 2026-03-10 13:53:53 +01:00
fbnic_fw_log.c fbnic: close fw_log race between users and teardown 2026-02-13 12:30:28 -08:00
fbnic_fw_log.h eth: fbnic: make fbnic_fw_log_write() parameter const 2025-09-18 11:37:23 +02:00
fbnic_fw.c fbnic: Set Relaxed Ordering PCIe TLP attributes for DMA engines 2026-03-31 16:05:19 +02:00
fbnic_fw.h eth fbnic: Add mailbox self test 2026-03-10 13:53:53 +01:00
fbnic_hw_stats.c eth: fbnic: Add pause stats support 2025-08-27 18:56:19 -07:00
fbnic_hw_stats.h eth: fbnic: Fetch TX pause storm stats 2026-03-05 16:26:52 +01:00
fbnic_hwmon.c eth: fbnic: Add hardware monitoring support via HWMON interface 2025-01-15 14:14:11 -08:00
fbnic_irq.c eth fbnic: Add msix self test 2026-03-10 13:53:53 +01:00
fbnic_mac.c eth: fbnic: Fetch TX pause storm stats 2026-03-05 16:26:52 +01:00
fbnic_mac.h eth: fbnic: Add protection against pause storm 2026-03-05 16:26:52 +01:00
fbnic_mdio.c fbnic: Add SW shim for MDIO interface to PMD and PCS 2025-11-27 10:41:31 +01:00
fbnic_netdev.c eth: fbnic: fix double-free of PCS on phylink creation failure 2026-05-07 12:34:42 +02:00
fbnic_netdev.h fbnic: convert to ndo_set_rx_mode_async 2026-04-21 12:50:24 +02:00
fbnic_pci.c fbnic: convert to ndo_set_rx_mode_async 2026-04-21 12:50:24 +02:00
fbnic_phylink.c fbnic: Replace use of internal PCS w/ Designware XPCS 2025-11-27 10:41:31 +01:00
fbnic_rpc.c fbnic: convert to ndo_set_rx_mode_async 2026-04-21 12:50:24 +02:00
fbnic_rpc.h fbnic: Add logic to repopulate RPC TCAM if BMC enables channel 2025-08-28 14:51:07 +02:00
fbnic_time.c eth: fbnic: fix various typos in comments and strings 2025-10-14 12:16:17 -07:00
fbnic_tlv.c eth fbnic: TLV support for use by MBX self test 2026-03-10 13:53:53 +01:00
fbnic_tlv.h eth fbnic: TLV support for use by MBX self test 2026-03-10 13:53:53 +01:00
fbnic_txrx.c eth: fbnic: Account for page fragments when updating BDQ tail 2026-03-27 20:30:23 -07:00
fbnic_txrx.h eth: fbnic: Increase FBNIC_QUEUE_SIZE_MIN to 64 2026-04-02 08:38:34 -07:00
fbnic.h fbnic: Set Relaxed Ordering PCIe TLP attributes for DMA engines 2026-03-31 16:05:19 +02:00
Makefile fbnic: Add SW shim for MDIO interface to PMD and PCS 2025-11-27 10:41:31 +01:00