| Message ID | 20230306151014.60913-2-schnelle@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | PCI: s390: Fix user-after-free and clean up | expand |
On Mon, Mar 06, 2023 at 04:10:11PM +0100, Niklas Schnelle wrote: > On s390 PCI functions may be hotplugged individually even when they > belong to a multi-function device. In particular on an SR-IOV device VFs > may be removed and later re-added. > > In commit a50297cf8235 ("s390/pci: separate zbus creation from > scanning") it was missed however that struct pci_bus and struct > zpci_bus's resource list retained a reference to the PCI functions MMIO > resources even though those resources are released and freed on > hot-unplug. These stale resources may subsequently be claimed when the > PCI function re-appears resulting in use-after-free. > > One idea of fixing this use-after-free in s390 specific code that was > investigated was to simply keep resources around from the moment a PCI > function first appeared until the whole virtual PCI bus created for > a multi-function device disappears. The problem with this however is > that due to the requirement of artificial MMIO addreesses (address > cookies) extra logic is then needed to keep the address cookies > compatible on re-plug. At the same time the MMIO resources semantically > belong to the PCI function so tying their lifecycle to the function > seems more logical. > > Instead a simpler approach is to remove the resources of an individually > hot-unplugged PCI function from the PCI bus's resource list while > keeping the resources of other PCI functions on the PCI bus untouched. > > This is done by introducing pci_bus_remove_resource() to remove an > individual resource. Similarly the resource also needs to be removed > from the struct zpci_bus's resource list. It turns out however, that > there is really no need to add the MMIO resources to the struct > zpci_bus's resource list at all and instead we can simply use the > zpci_bar_struct's resource pointer directly. > > Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> The meat of this is mostly in s390, so I think it makes more sense to merge via that tree. But let me know if you'd rather that I take it. > --- > v1 -> v2: > - Remove return at the end of function returning void > > arch/s390/pci/pci.c | 16 ++++++++++------ > arch/s390/pci/pci_bus.c | 12 +++++------- > arch/s390/pci/pci_bus.h | 3 +-- > drivers/pci/bus.c | 21 +++++++++++++++++++++ > include/linux/pci.h | 1 + > 5 files changed, 38 insertions(+), 15 deletions(-) > > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c > index ef38b1514c77..e16afacc8fd1 100644 > --- a/arch/s390/pci/pci.c > +++ b/arch/s390/pci/pci.c > @@ -544,8 +544,7 @@ static struct resource *__alloc_res(struct zpci_dev *zdev, unsigned long start, > return r; > } > > -int zpci_setup_bus_resources(struct zpci_dev *zdev, > - struct list_head *resources) > +int zpci_setup_bus_resources(struct zpci_dev *zdev) > { > unsigned long addr, size, flags; > struct resource *res; > @@ -581,7 +580,6 @@ int zpci_setup_bus_resources(struct zpci_dev *zdev, > return -ENOMEM; > } > zdev->bars[i].res = res; > - pci_add_resource(resources, res); > } > zdev->has_resources = 1; > > @@ -590,17 +588,23 @@ int zpci_setup_bus_resources(struct zpci_dev *zdev, > > static void zpci_cleanup_bus_resources(struct zpci_dev *zdev) > { > + struct resource *res; > int i; > > + pci_lock_rescan_remove(); > for (i = 0; i < PCI_STD_NUM_BARS; i++) { > - if (!zdev->bars[i].size || !zdev->bars[i].res) > + res = zdev->bars[i].res; > + if (!res) > continue; > > + release_resource(res); > + pci_bus_remove_resource(zdev->zbus->bus, res); > zpci_free_iomap(zdev, zdev->bars[i].map_idx); > - release_resource(zdev->bars[i].res); > - kfree(zdev->bars[i].res); > + zdev->bars[i].res = NULL; > + kfree(res); > } > zdev->has_resources = 0; > + pci_unlock_rescan_remove(); > } > > int pcibios_device_add(struct pci_dev *pdev) > diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c > index 6a8da1b742ae..a99926af2b69 100644 > --- a/arch/s390/pci/pci_bus.c > +++ b/arch/s390/pci/pci_bus.c > @@ -41,9 +41,7 @@ static int zpci_nb_devices; > */ > static int zpci_bus_prepare_device(struct zpci_dev *zdev) > { > - struct resource_entry *window, *n; > - struct resource *res; > - int rc; > + int rc, i; > > if (!zdev_enabled(zdev)) { > rc = zpci_enable_device(zdev); > @@ -57,10 +55,10 @@ static int zpci_bus_prepare_device(struct zpci_dev *zdev) > } > > if (!zdev->has_resources) { > - zpci_setup_bus_resources(zdev, &zdev->zbus->resources); > - resource_list_for_each_entry_safe(window, n, &zdev->zbus->resources) { > - res = window->res; > - pci_bus_add_resource(zdev->zbus->bus, res, 0); > + zpci_setup_bus_resources(zdev); > + for (i = 0; i < PCI_STD_NUM_BARS; i++) { > + if (zdev->bars[i].res) > + pci_bus_add_resource(zdev->zbus->bus, zdev->bars[i].res, 0); > } > } > > diff --git a/arch/s390/pci/pci_bus.h b/arch/s390/pci/pci_bus.h > index e96c9860e064..af9f0ac79a1b 100644 > --- a/arch/s390/pci/pci_bus.h > +++ b/arch/s390/pci/pci_bus.h > @@ -30,8 +30,7 @@ static inline void zpci_zdev_get(struct zpci_dev *zdev) > > int zpci_alloc_domain(int domain); > void zpci_free_domain(int domain); > -int zpci_setup_bus_resources(struct zpci_dev *zdev, > - struct list_head *resources); > +int zpci_setup_bus_resources(struct zpci_dev *zdev); > > static inline struct zpci_dev *zdev_from_bus(struct pci_bus *bus, > unsigned int devfn) > diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c > index 83ae838ceb5f..549c4bd5caec 100644 > --- a/drivers/pci/bus.c > +++ b/drivers/pci/bus.c > @@ -76,6 +76,27 @@ struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n) > } > EXPORT_SYMBOL_GPL(pci_bus_resource_n); > > +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res) > +{ > + struct pci_bus_resource *bus_res, *tmp; > + int i; > + > + for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) { > + if (bus->resource[i] == res) { > + bus->resource[i] = NULL; > + return; > + } > + } > + > + list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) { > + if (bus_res->res == res) { > + list_del(&bus_res->list); > + kfree(bus_res); > + return; > + } > + } > +} > + > void pci_bus_remove_resources(struct pci_bus *bus) > { > int i; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index fafd8020c6d7..b50e5c79f7e3 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1438,6 +1438,7 @@ void pci_bus_add_resource(struct pci_bus *bus, struct resource *res, > unsigned int flags); > struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n); > void pci_bus_remove_resources(struct pci_bus *bus); > +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res); > int devm_request_pci_bus_resources(struct device *dev, > struct list_head *resources); > > -- > 2.37.2 >
On Wed, 2023-03-08 at 17:14 -0600, Bjorn Helgaas wrote: > On Mon, Mar 06, 2023 at 04:10:11PM +0100, Niklas Schnelle wrote: > > On s390 PCI functions may be hotplugged individually even when they > > belong to a multi-function device. In particular on an SR-IOV device VFs > > may be removed and later re-added. > > > > In commit a50297cf8235 ("s390/pci: separate zbus creation from > > scanning") it was missed however that struct pci_bus and struct > > zpci_bus's resource list retained a reference to the PCI functions MMIO > > resources even though those resources are released and freed on > > hot-unplug. These stale resources may subsequently be claimed when the > > PCI function re-appears resulting in use-after-free. > > > > One idea of fixing this use-after-free in s390 specific code that was > > investigated was to simply keep resources around from the moment a PCI > > function first appeared until the whole virtual PCI bus created for > > a multi-function device disappears. The problem with this however is > > that due to the requirement of artificial MMIO addreesses (address > > cookies) extra logic is then needed to keep the address cookies > > compatible on re-plug. At the same time the MMIO resources semantically > > belong to the PCI function so tying their lifecycle to the function > > seems more logical. > > > > Instead a simpler approach is to remove the resources of an individually > > hot-unplugged PCI function from the PCI bus's resource list while > > keeping the resources of other PCI functions on the PCI bus untouched. > > > > This is done by introducing pci_bus_remove_resource() to remove an > > individual resource. Similarly the resource also needs to be removed > > from the struct zpci_bus's resource list. It turns out however, that > > there is really no need to add the MMIO resources to the struct > > zpci_bus's resource list at all and instead we can simply use the > > zpci_bar_struct's resource pointer directly. > > > > Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > Acked-by: Bjorn Helgaas <bhelgaas@google.com> > > The meat of this is mostly in s390, so I think it makes more sense to > merge via that tree. But let me know if you'd rather that I take it. > > Thanks for taking a look and the valuable suggestions. I'll coordinate with Vasily to take this via the s390 tree. As for the locking I agree it is out of scope for this series. Meant more that the resource handling might be a good place to start splitting up the pci_rescan_remove_lock and that I might take a look at that if I find the time which of course we're all lacking. Regards, Niklas
On 3/6/23 10:10 AM, Niklas Schnelle wrote: > On s390 PCI functions may be hotplugged individually even when they > belong to a multi-function device. In particular on an SR-IOV device VFs > may be removed and later re-added. > > In commit a50297cf8235 ("s390/pci: separate zbus creation from > scanning") it was missed however that struct pci_bus and struct > zpci_bus's resource list retained a reference to the PCI functions MMIO > resources even though those resources are released and freed on > hot-unplug. These stale resources may subsequently be claimed when the > PCI function re-appears resulting in use-after-free. > > One idea of fixing this use-after-free in s390 specific code that was > investigated was to simply keep resources around from the moment a PCI > function first appeared until the whole virtual PCI bus created for > a multi-function device disappears. The problem with this however is > that due to the requirement of artificial MMIO addreesses (address > cookies) extra logic is then needed to keep the address cookies > compatible on re-plug. At the same time the MMIO resources semantically > belong to the PCI function so tying their lifecycle to the function > seems more logical. > > Instead a simpler approach is to remove the resources of an individually > hot-unplugged PCI function from the PCI bus's resource list while > keeping the resources of other PCI functions on the PCI bus untouched. > > This is done by introducing pci_bus_remove_resource() to remove an > individual resource. Similarly the resource also needs to be removed > from the struct zpci_bus's resource list. It turns out however, that > there is really no need to add the MMIO resources to the struct > zpci_bus's resource list at all and instead we can simply use the > zpci_bar_struct's resource pointer directly. > > Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
On Wed, Mar 08, 2023 at 05:14:49PM -0600, Bjorn Helgaas wrote: > On Mon, Mar 06, 2023 at 04:10:11PM +0100, Niklas Schnelle wrote: > > On s390 PCI functions may be hotplugged individually even when they > > belong to a multi-function device. In particular on an SR-IOV device VFs > > may be removed and later re-added. > > > > In commit a50297cf8235 ("s390/pci: separate zbus creation from > > scanning") it was missed however that struct pci_bus and struct > > zpci_bus's resource list retained a reference to the PCI functions MMIO > > resources even though those resources are released and freed on > > hot-unplug. These stale resources may subsequently be claimed when the > > PCI function re-appears resulting in use-after-free. > > > > One idea of fixing this use-after-free in s390 specific code that was > > investigated was to simply keep resources around from the moment a PCI > > function first appeared until the whole virtual PCI bus created for > > a multi-function device disappears. The problem with this however is > > that due to the requirement of artificial MMIO addreesses (address > > cookies) extra logic is then needed to keep the address cookies > > compatible on re-plug. At the same time the MMIO resources semantically > > belong to the PCI function so tying their lifecycle to the function > > seems more logical. > > > > Instead a simpler approach is to remove the resources of an individually > > hot-unplugged PCI function from the PCI bus's resource list while > > keeping the resources of other PCI functions on the PCI bus untouched. > > > > This is done by introducing pci_bus_remove_resource() to remove an > > individual resource. Similarly the resource also needs to be removed > > from the struct zpci_bus's resource list. It turns out however, that > > there is really no need to add the MMIO resources to the struct > > zpci_bus's resource list at all and instead we can simply use the > > zpci_bar_struct's resource pointer directly. > > > > Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > Acked-by: Bjorn Helgaas <bhelgaas@google.com> > > The meat of this is mostly in s390, so I think it makes more sense to > merge via that tree. But let me know if you'd rather that I take it. I'll take it via s390 tree. Thanks
On Mon, Mar 06, 2023 at 04:10:11PM +0100, Niklas Schnelle wrote: > --- a/drivers/pci/bus.c > +++ b/drivers/pci/bus.c > @@ -76,6 +76,27 @@ struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n) > } > EXPORT_SYMBOL_GPL(pci_bus_resource_n); > > +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res) > +{ > + struct pci_bus_resource *bus_res, *tmp; > + int i; > + > + for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) { > + if (bus->resource[i] == res) { > + bus->resource[i] = NULL; > + return; > + } > + } > + > + list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) { > + if (bus_res->res == res) { > + list_del(&bus_res->list); > + kfree(bus_res); > + return; > + } > + } > +} I realize this has already been applied so s390.git/master, but nevertheless would like to point out there's a handy pci_bus_for_each_resource() helper which could have been used here instead of the for-loop. Sorry for chiming in late, I just spotted this while flushing out my inbox. Adding Andy to cc: who's been active in this area recently. Thanks, Lukas
On Mon, Apr 17, 2023 at 10:46 AM Lukas Wunner <lukas@wunner.de> wrote: > On Mon, Mar 06, 2023 at 04:10:11PM +0100, Niklas Schnelle wrote: ... > > +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res) > > +{ > > + struct pci_bus_resource *bus_res, *tmp; > > + int i; > > + > > + for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) { > > + if (bus->resource[i] == res) { > > + bus->resource[i] = NULL; > > + return; > > + } > > + } > > + > > + list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) { > > + if (bus_res->res == res) { > > + list_del(&bus_res->list); > > + kfree(bus_res); > > + return; > > + } > > + } > > +} > > I realize this has already been applied so s390.git/master, > but nevertheless would like to point out there's a handy > pci_bus_for_each_resource() helper which could have been > used here instead of the for-loop. Actually in this case it's not possible. The above code nullifies the matched resource or removes it from the list. We don't have any good iterator inside pci_bus_for_each_resource() to do the latter. There might be other places in the kernel code where something like above is used and we can split a separate helper exactly for matching cases, but with the above context I dunno we need to do anything right now. P.S. Thanks for Cc'ing me.
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index ef38b1514c77..e16afacc8fd1 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -544,8 +544,7 @@ static struct resource *__alloc_res(struct zpci_dev *zdev, unsigned long start, return r; } -int zpci_setup_bus_resources(struct zpci_dev *zdev, - struct list_head *resources) +int zpci_setup_bus_resources(struct zpci_dev *zdev) { unsigned long addr, size, flags; struct resource *res; @@ -581,7 +580,6 @@ int zpci_setup_bus_resources(struct zpci_dev *zdev, return -ENOMEM; } zdev->bars[i].res = res; - pci_add_resource(resources, res); } zdev->has_resources = 1; @@ -590,17 +588,23 @@ int zpci_setup_bus_resources(struct zpci_dev *zdev, static void zpci_cleanup_bus_resources(struct zpci_dev *zdev) { + struct resource *res; int i; + pci_lock_rescan_remove(); for (i = 0; i < PCI_STD_NUM_BARS; i++) { - if (!zdev->bars[i].size || !zdev->bars[i].res) + res = zdev->bars[i].res; + if (!res) continue; + release_resource(res); + pci_bus_remove_resource(zdev->zbus->bus, res); zpci_free_iomap(zdev, zdev->bars[i].map_idx); - release_resource(zdev->bars[i].res); - kfree(zdev->bars[i].res); + zdev->bars[i].res = NULL; + kfree(res); } zdev->has_resources = 0; + pci_unlock_rescan_remove(); } int pcibios_device_add(struct pci_dev *pdev) diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c index 6a8da1b742ae..a99926af2b69 100644 --- a/arch/s390/pci/pci_bus.c +++ b/arch/s390/pci/pci_bus.c @@ -41,9 +41,7 @@ static int zpci_nb_devices; */ static int zpci_bus_prepare_device(struct zpci_dev *zdev) { - struct resource_entry *window, *n; - struct resource *res; - int rc; + int rc, i; if (!zdev_enabled(zdev)) { rc = zpci_enable_device(zdev); @@ -57,10 +55,10 @@ static int zpci_bus_prepare_device(struct zpci_dev *zdev) } if (!zdev->has_resources) { - zpci_setup_bus_resources(zdev, &zdev->zbus->resources); - resource_list_for_each_entry_safe(window, n, &zdev->zbus->resources) { - res = window->res; - pci_bus_add_resource(zdev->zbus->bus, res, 0); + zpci_setup_bus_resources(zdev); + for (i = 0; i < PCI_STD_NUM_BARS; i++) { + if (zdev->bars[i].res) + pci_bus_add_resource(zdev->zbus->bus, zdev->bars[i].res, 0); } } diff --git a/arch/s390/pci/pci_bus.h b/arch/s390/pci/pci_bus.h index e96c9860e064..af9f0ac79a1b 100644 --- a/arch/s390/pci/pci_bus.h +++ b/arch/s390/pci/pci_bus.h @@ -30,8 +30,7 @@ static inline void zpci_zdev_get(struct zpci_dev *zdev) int zpci_alloc_domain(int domain); void zpci_free_domain(int domain); -int zpci_setup_bus_resources(struct zpci_dev *zdev, - struct list_head *resources); +int zpci_setup_bus_resources(struct zpci_dev *zdev); static inline struct zpci_dev *zdev_from_bus(struct pci_bus *bus, unsigned int devfn) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 83ae838ceb5f..549c4bd5caec 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -76,6 +76,27 @@ struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n) } EXPORT_SYMBOL_GPL(pci_bus_resource_n); +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res) +{ + struct pci_bus_resource *bus_res, *tmp; + int i; + + for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) { + if (bus->resource[i] == res) { + bus->resource[i] = NULL; + return; + } + } + + list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) { + if (bus_res->res == res) { + list_del(&bus_res->list); + kfree(bus_res); + return; + } + } +} + void pci_bus_remove_resources(struct pci_bus *bus) { int i; diff --git a/include/linux/pci.h b/include/linux/pci.h index fafd8020c6d7..b50e5c79f7e3 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1438,6 +1438,7 @@ void pci_bus_add_resource(struct pci_bus *bus, struct resource *res, unsigned int flags); struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n); void pci_bus_remove_resources(struct pci_bus *bus); +void pci_bus_remove_resource(struct pci_bus *bus, struct resource *res); int devm_request_pci_bus_resources(struct device *dev, struct list_head *resources);
On s390 PCI functions may be hotplugged individually even when they belong to a multi-function device. In particular on an SR-IOV device VFs may be removed and later re-added. In commit a50297cf8235 ("s390/pci: separate zbus creation from scanning") it was missed however that struct pci_bus and struct zpci_bus's resource list retained a reference to the PCI functions MMIO resources even though those resources are released and freed on hot-unplug. These stale resources may subsequently be claimed when the PCI function re-appears resulting in use-after-free. One idea of fixing this use-after-free in s390 specific code that was investigated was to simply keep resources around from the moment a PCI function first appeared until the whole virtual PCI bus created for a multi-function device disappears. The problem with this however is that due to the requirement of artificial MMIO addreesses (address cookies) extra logic is then needed to keep the address cookies compatible on re-plug. At the same time the MMIO resources semantically belong to the PCI function so tying their lifecycle to the function seems more logical. Instead a simpler approach is to remove the resources of an individually hot-unplugged PCI function from the PCI bus's resource list while keeping the resources of other PCI functions on the PCI bus untouched. This is done by introducing pci_bus_remove_resource() to remove an individual resource. Similarly the resource also needs to be removed from the struct zpci_bus's resource list. It turns out however, that there is really no need to add the MMIO resources to the struct zpci_bus's resource list at all and instead we can simply use the zpci_bar_struct's resource pointer directly. Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> --- v1 -> v2: - Remove return at the end of function returning void arch/s390/pci/pci.c | 16 ++++++++++------ arch/s390/pci/pci_bus.c | 12 +++++------- arch/s390/pci/pci_bus.h | 3 +-- drivers/pci/bus.c | 21 +++++++++++++++++++++ include/linux/pci.h | 1 + 5 files changed, 38 insertions(+), 15 deletions(-)