| Message ID | 20220711134520.10466-1-ihuguet@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] sfc: fix use after free when disabling sriov | expand |
On Mon, 11 Jul 2022 15:45:20 +0200 Íñigo Huguet wrote: > Use after free is detected by kfence when disabling sriov. What was read > after being freed was vf->pci_dev: it was freed from pci_disable_sriov > and later read in efx_ef10_sriov_free_vf_vports, called from > efx_ef10_sriov_free_vf_vswitching. > > Set the pointer to NULL at release time to not trying to read it later. Please add a Fixes tag and repost. Does ef100 need the same fix? :(
On Tue, Jul 12, 2022 at 5:39 AM Jakub Kicinski <kuba@kernel.org> wrote: > > On Mon, 11 Jul 2022 15:45:20 +0200 Íñigo Huguet wrote: > > Use after free is detected by kfence when disabling sriov. What was read > > after being freed was vf->pci_dev: it was freed from pci_disable_sriov > > and later read in efx_ef10_sriov_free_vf_vports, called from > > efx_ef10_sriov_free_vf_vswitching. > > > > Set the pointer to NULL at release time to not trying to read it later. > > Please add a Fixes tag and repost. Does ef100 need the same fix? :( > OK, will do. ef100 doesn't seem to need this, but I can't test because I don't have any of these cards.
diff --git a/drivers/net/ethernet/sfc/ef10_sriov.c b/drivers/net/ethernet/sfc/ef10_sriov.c index 7f5aa4a8c451..92550c7e85ce 100644 --- a/drivers/net/ethernet/sfc/ef10_sriov.c +++ b/drivers/net/ethernet/sfc/ef10_sriov.c @@ -408,8 +408,9 @@ static int efx_ef10_pci_sriov_enable(struct efx_nic *efx, int num_vfs) static int efx_ef10_pci_sriov_disable(struct efx_nic *efx, bool force) { struct pci_dev *dev = efx->pci_dev; + struct efx_ef10_nic_data *nic_data = efx->nic_data; unsigned int vfs_assigned = pci_vfs_assigned(dev); - int rc = 0; + int i, rc = 0; if (vfs_assigned && !force) { netif_info(efx, drv, efx->net_dev, "VFs are assigned to guests; " @@ -417,10 +418,13 @@ static int efx_ef10_pci_sriov_disable(struct efx_nic *efx, bool force) return -EBUSY; } - if (!vfs_assigned) + if (!vfs_assigned) { + for (i = 0; i < efx->vf_count; i++) + nic_data->vf[i].pci_dev = NULL; pci_disable_sriov(dev); - else + } else { rc = -EBUSY; + } efx_ef10_sriov_free_vf_vswitching(efx); efx->vf_count = 0;
Use after free is detected by kfence when disabling sriov. What was read after being freed was vf->pci_dev: it was freed from pci_disable_sriov and later read in efx_ef10_sriov_free_vf_vports, called from efx_ef10_sriov_free_vf_vswitching. Set the pointer to NULL at release time to not trying to read it later. Reproducer and dmesg log (note that kfence doesn't detect it every time): $ echo 1 > /sys/class/net/enp65s0f0np0/device/sriov_numvfs $ echo 0 > /sys/class/net/enp65s0f0np0/device/sriov_numvfs BUG: KFENCE: use-after-free read in efx_ef10_sriov_free_vf_vswitching+0x82/0x170 [sfc] Use-after-free read at 0x00000000ff3c1ba5 (in kfence-#224): efx_ef10_sriov_free_vf_vswitching+0x82/0x170 [sfc] efx_ef10_pci_sriov_disable+0x38/0x70 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xfe/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae kfence-#224: 0x00000000edb8ef95-0x00000000671f5ce1, size=2792, cache=kmalloc-4k allocated by task 6771 on cpu 10 at 3137.860196s: pci_alloc_dev+0x21/0x60 pci_iov_add_virtfn+0x2a2/0x320 sriov_enable+0x212/0x3e0 efx_ef10_sriov_configure+0x67/0x80 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xba/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae freed by task 6771 on cpu 12 at 3170.991309s: device_release+0x34/0x90 kobject_cleanup+0x3a/0x130 pci_iov_remove_virtfn+0xd9/0x120 sriov_disable+0x30/0xe0 efx_ef10_pci_sriov_disable+0x57/0x70 [sfc] efx_pci_sriov_configure+0x24/0x40 [sfc] sriov_numvfs_store+0xfe/0x140 kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x11f/0x1b0 vfs_write+0x1eb/0x280 ksys_write+0x5f/0xe0 do_syscall_64+0x5c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Reported-by: Yanghang Liu <yanghliu@redhat.com> Signed-off-by: Íñigo Huguet <ihuguet@redhat.com> --- drivers/net/ethernet/sfc/ef10_sriov.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)