kernel/linux.git/drivers/base/core.c, branch v6.6.132

driver core: fix potential NULL pointer dereference in dev_uevent()

2025-05-02T05:51:03+00:00

commit 18daa52418e7e4629ed1703b64777294209d2622 upstream. If userspace reads "uevent" device attribute at the same time as another threads unbinds the device from its driver, change to dev->driver from a valid pointer to NULL may result in crash. Fix this by using READ_ONCE() when fetching the pointer, and take bus' drivers klist lock to make sure driver instance will not disappear while we access it. Use WRITE_ONCE() when setting the driver pointer to ensure there is no tearing. Signed-off-by: Dmitry Torokhov Reviewed-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman

driver core: introduce device_set_driver() helper

2025-05-02T05:51:03+00:00

commit 04d3e5461c1f5cf8eec964ab64948ebed826e95e upstream. In preparation to closing a race when reading driver pointer in dev_uevent() code, instead of setting device->driver pointer directly introduce device_set_driver() helper. Signed-off-by: Dmitry Torokhov Reviewed-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250311052417.1846985-2-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman

Revert "drivers: core: synchronize really_probe() and dev_uevent()"

2025-05-02T05:51:02+00:00

commit dc1771f718548f7d4b93991b174c6e7b5e1ba410 upstream. This reverts commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0. Probing a device can take arbitrary long time. In the field we observed that, for example, probing a bad micro-SD cards in an external USB card reader (or maybe cards were good but cables were flaky) sometimes takes longer than 2 minutes due to multiple retries at various levels of the stack. We can not block uevent_show() method for that long because udev is reading that attribute very often and that blocks udev and interferes with booting of the system. The change that introduced locking was concerned with dev_uevent() racing with unbinding the driver. However we can handle it without locking (which will be done in subsequent patch). There was also claim that synchronization with probe() is needed to properly load USB drivers, however this is a red herring: the change adding the lock was introduced in May of last year and USB loading and probing worked properly for many years before that. Revert the harmful locking. Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov Reviewed-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250311052417.1846985-1-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman

drivers: core: fix device leak in __fw_devlink_relax_cycles()

2025-03-13T11:58:37+00:00

commit 78eb41f518f414378643ab022241df2a9dcd008b upstream. Commit bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") introduced a new struct device *con_dev and a get_dev_from_fwnode() call to get it, but without adding a corresponding put_device(). Closes: https://lore.kernel.org/all/20241204124826.2e055091@booty/ Fixes: bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") Cc: stable@vger.kernel.org Reviewed-by: Saravana Kannan Signed-off-by: Luca Ceresoli Link: https://lore.kernel.org/r/20250213-fix__fw_devlink_relax_cycles_missing_device_put-v2-1-8cd3b03e6a3f@bootlin.com Signed-off-by: Greg Kroah-Hartman

driver core: fw_devlink: Stop trying to optimize cycle detection logic

2024-12-14T18:59:45+00:00

[ Upstream commit bac3b10b78e54b7da3cede397258f75a2180609b ] In attempting to optimize fw_devlink runtime, I introduced numerous cycle detection bugs by foregoing cycle detection logic under specific conditions. Each fix has further narrowed the conditions for optimization. It's time to give up on these optimization attempts and just run the cycle detection logic every time fw_devlink tries to create a device link. The specific bug report that triggered this fix involved a supplier fwnode that never gets a device created for it. Instead, the supplier fwnode is represented by the device that corresponds to an ancestor fwnode. In this case, fw_devlink didn't do any cycle detection because the cycle detection logic is only run when a device link is created between the devices that correspond to the actual consumer and supplier fwnodes. With this change, fw_devlink will run cycle detection logic even when creating SYNC_STATE_ONLY proxy device links from a device that is an ancestor of a consumer fwnode. Reported-by: Tomi Valkeinen Closes: https://lore.kernel.org/all/1a1ab663-d068-40fb-8c94-f0715403d276@ideasonboard.com/ Fixes: 6442d79d880c ("driver core: fw_devlink: Improve detection of overlapping cycles") Cc: stable Tested-by: Tomi Valkeinen Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20241030171009.1853340-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

driver core: Add FWLINK_FLAG_IGNORE to completely ignore a fwnode link

2024-12-14T18:59:45+00:00

[ Upstream commit b7e1241d8f77ed64404a5e4450f43a319310fc91 ] A fwnode link between specific supplier-consumer fwnodes can be added multiple times for multiple reasons. If that dependency doesn't exist, deleting the fwnode link once doesn't guarantee that it won't get created again. So, add FWLINK_FLAG_IGNORE flag to mark a fwnode link as one that needs to be completely ignored. Since a fwnode link's flags is an OR of all the flags passed to all the fwnode_link_add() calls to create that specific fwnode link, the FWLINK_FLAG_IGNORE flag is preserved and can be used to mark a fwnode link as on that need to be completely ignored until it is deleted. Signed-off-by: Saravana Kannan Acked-by: "Rafael J. Wysocki" Reviewed-by: Rob Herring Link: https://lore.kernel.org/r/20240305050458.1400667-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") Signed-off-by: Sasha Levin

driver core: fw_devlink: Improve logs for cycle detection

2024-12-14T18:59:44+00:00

[ Upstream commit 6e7ad1aebb4fc9fed0217dd50ef6e58a53f17d81 ] The links in a cycle are not all logged in a consistent manner or not logged at all. Make them consistent by adding a "cycle:" string and log all the link in the cycles (even the child ==> parent dependency) so that it's easier to debug cycle detection code. Also, mark the start and end of a cycle so it's easy to tell when multiple cycles are logged back to back. Signed-off-by: Saravana Kannan Tested-by: Xu Yang Link: https://lore.kernel.org/r/20240202095636.868578-4-saravanak@google.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: bac3b10b78e5 ("driver core: fw_devlink: Stop trying to optimize cycle detection logic") Signed-off-by: Sasha Levin

cxl/port: Fix use-after-free, permit out-of-order decoder shutdown

2024-11-08T15:28:24+00:00

commit 101c268bd2f37e965a5468353e62d154db38838e upstream. In support of investigating an initialization failure report [1], cxl_test was updated to register mock memory-devices after the mock root-port/bus device had been registered. That led to cxl_test crashing with a use-after-free bug with the following signature: cxl_port_attach_region: cxl region3: cxl_host_bridge.0:port3 decoder3.0 add: mem0:decoder7.0 @ 0 next: cxl_switch_uport.0 nr_eps: 1 nr_targets: 1 cxl_port_attach_region: cxl region3: cxl_host_bridge.0:port3 decoder3.0 add: mem4:decoder14.0 @ 1 next: cxl_switch_uport.0 nr_eps: 2 nr_targets: 1 cxl_port_setup_targets: cxl region3: cxl_switch_uport.0:port6 target[0] = cxl_switch_dport.0 for mem0:decoder7.0 @ 0 1) cxl_port_setup_targets: cxl region3: cxl_switch_uport.0:port6 target[1] = cxl_switch_dport.4 for mem4:decoder14.0 @ 1 [..] cxld_unregister: cxl decoder14.0: cxl_region_decode_reset: cxl_region region3: mock_decoder_reset: cxl_port port3: decoder3.0 reset 2) mock_decoder_reset: cxl_port port3: decoder3.0: out of order reset, expected decoder3.1 cxl_endpoint_decoder_release: cxl decoder14.0: [..] cxld_unregister: cxl decoder7.0: 3) cxl_region_decode_reset: cxl_region region3: Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6bc3: 0000 [#1] PREEMPT SMP PTI [..] RIP: 0010:to_cxl_port+0x8/0x60 [cxl_core] [..] Call Trace: cxl_region_decode_reset+0x69/0x190 [cxl_core] cxl_region_detach+0xe8/0x210 [cxl_core] cxl_decoder_kill_region+0x27/0x40 [cxl_core] cxld_unregister+0x5d/0x60 [cxl_core] At 1) a region has been established with 2 endpoint decoders (7.0 and 14.0). Those endpoints share a common switch-decoder in the topology (3.0). At teardown, 2), decoder14.0 is the first to be removed and hits the "out of order reset case" in the switch decoder. The effect though is that region3 cleanup is aborted leaving it in-tact and referencing decoder14.0. At 3) the second attempt to teardown region3 trips over the stale decoder14.0 object which has long since been deleted. The fix here is to recognize that the CXL specification places no mandate on in-order shutdown of switch-decoders, the driver enforces in-order allocation, and hardware enforces in-order commit. So, rather than fail and leave objects dangling, always remove them. In support of making cxl_region_decode_reset() always succeed, cxl_region_invalidate_memregion() failures are turned into warnings. Crashing the kernel is ok there since system integrity is at risk if caches cannot be managed around physical address mutation events like CXL region destruction. A new device_for_each_child_reverse_from() is added to cleanup port->commit_end after all dependent decoders have been disabled. In other words if decoders are allocated 0->1->2 and disabled 1->2->0 then port->commit_end only decrements from 2 after 2 has been disabled, and it decrements all the way to zero since 1 was disabled previously. Link: http://lore.kernel.org/20241004212504.1246-1-gourry@gourry.net [1] Cc: stable@vger.kernel.org Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware") Reviewed-by: Jonathan Cameron Cc: Greg Kroah-Hartman Cc: Davidlohr Bueso Cc: Dave Jiang Cc: Alison Schofield Cc: Ira Weiny Cc: Zijun Hu Signed-off-by: Dan Williams Reviewed-by: Ira Weiny Link: https://patch.msgid.link/172964782781.81806.17902885593105284330.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Ira Weiny Signed-off-by: Greg Kroah-Hartman

Revert "driver core: Fix uevent_show() vs driver detach race"

2024-11-08T15:28:23+00:00

commit 9a71892cbcdb9d1459c84f5a4c722b14354158a5 upstream. This reverts commit 15fffc6a5624b13b428bb1c6e9088e32a55eb82c. This commit causes a regression, so revert it for now until it can come back in a way that works for everyone. Link: https://lore.kernel.org/all/172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com/ Fixes: 15fffc6a5624 ("driver core: Fix uevent_show() vs driver detach race") Cc: stable Cc: Ashish Sangwan Cc: Namjae Jeon Cc: Dirk Behme Cc: Greg Kroah-Hartman Cc: Rafael J. Wysocki Cc: Dan Williams Signed-off-by: Greg Kroah-Hartman

driver core: Fix error handling in driver API device_rename()

2024-10-04T14:29:39+00:00

[ Upstream commit 6d8249ac29bc23260dfa9747eb398ce76012d73c ] For class-device, device_rename() failure maybe cause unexpected link name within its class folder as explained below: /sys/class/.../old_name -> /sys/devices/.../old_name device_rename(..., new_name) and failed /sys/class/.../new_name -> /sys/devices/.../old_name Fixed by undoing renaming link if renaming kobject failed. Fixes: f349cf34731c ("driver core: Implement ns directory support for device classes.") Signed-off-by: Zijun Hu Link: https://lore.kernel.org/r/20240722-device_rename_fix-v2-1-77de1a6c6495@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin