Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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Johan Hovold <johan@kernel.org> says:
The new buffer management code has not been tested or reviewed properly
and breaks boot of machines like the Lenovo ThinkPad X13s.
Fixing this will require designing a proper interface for managing these
transactions, something which most likely involves reverting most of the
offending commit anyway.
Revert the broken code to fix the regression and let Intel come up with
a properly tested implementation for a later kernel.
Link: https://lore.kernel.org/r/20251222152204.2846-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 14ad4c10d5bdd413ff9a914260e89b5f54b7a2c7.
The originally offending commit will be reverted instead of this fix up
at this point in time, so revert this fix.
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: stable <stable@kernel.org>
Cc: Johan Hovold <johan@kernel.org>
Fixes: 14ad4c10d5bd ("usb: typec: ucsi: Fix null pointer dereference in ucsi_sync_control_common")
Link: https://lore.kernel.org/r/20251222152204.2846-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 3e082978c33151d576694deac8abde021ea669a8.
The new buffer management code has not been tested or reviewed properly
and breaks boot of machines like the Lenovo ThinkPad X13s:
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000000
CPU: 0 UID: 0 PID: 813 Comm: kworker/0:3 Not tainted 6.19.0-rc2 #26 PREEMPT
Hardware name: LENOVO 21BYZ9SRUS/21BYZ9SRUS, BIOS N3HET87W (1.59 ) 12/05/2023
Workqueue: events ucsi_handle_connector_change [typec_ucsi]
Call trace:
ucsi_sync_control_common+0xe4/0x1ec [typec_ucsi] (P)
ucsi_run_command+0xcc/0x194 [typec_ucsi]
ucsi_send_command_common+0x84/0x2a0 [typec_ucsi]
ucsi_get_connector_status+0x48/0x78 [typec_ucsi]
ucsi_handle_connector_change+0x5c/0x4f4 [typec_ucsi]
process_one_work+0x208/0x60c
worker_thread+0x244/0x388
The new code completely ignores concurrency so that the message length
can be updated while a transaction is ongoing. In the above case, the
length ends up being modified by another thread while processing an ack
so that the NULL cci pointer is dereferenced.
Fixing this will require designing a proper interface for managing these
transactions, something which most likely involves reverting most of the
offending commit anyway.
Revert the broken code to fix the regression and let Intel come up with
a properly tested implementation for a later kernel.
Fixes: 3e082978c331 ("usb: typec: ucsi: Update UCSI structure to have message in and message out fields")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/20251222152204.2846-5-johan@kernel.org
This reverts commit 5106dbab44fba8ec6dede3f4e75d17f5aa777ec8.
There are reported issues in this file, so revert the commit for now so
that the original offending changes can be reverted and working systems
can be restored. This can come back at a later time if it is rebased
yet-again (sorry.)
Cc: stable <stable@kernel.org>
Cc: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20251222152204.2846-1-johan@kernel.org
Fixes: 5106dbab44fb ("usb: typec: ucsi: Get connector status after enable notifications")
Cc: Kenneth R. Crudup <kenny@panix.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Hsin-Te Yuan <yuanhsinte@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit db0028637cc832add6d87564fcc2ebb12781b046.
The new buffer management code that this feature relies on is broken so
revert for now.
As for the in buffer, nothing prevents the out message size and buffer
from being modified while the message is being processed due to lack of
serialisation.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/20251222152204.2846-4-johan@kernel.org
Error labels should be named after what they do rather than after from
where they are jumped to.
Rename the probe error labels for consistency and to improve
readability.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251218153519.19453-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 775fae520e6ae62c393a8daf42dc534f09692f3f.
The new buffer management code that this relies on is broken so revert
for now.
It also looks like the error handling needs some more thought as the
message out size is not reset on errors.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/20251222152204.2846-3-johan@kernel.org
Error labels should be named after what they do rather than after from
where they are jumped to.
Rename the probe error labels for consistency and to improve
readability.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251218153519.19453-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 1b474ee01fbb73b1365adbf9b3067f7375e471ee.
The new buffer management code that this feature relies on is broken so
revert for now.
The interface for writing data and support for UCSI_SET_PDOS looks like
it could use some more thought as well.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/20251222152204.2846-2-johan@kernel.org
Make sure to drop the reference taken when looking up the PHY I2C device
during probe on probe failure (e.g. probe deferral) and on driver
unbind.
Fixes: 73108aa90cbf ("USB: ohci-nxp: Use isp1301 driver")
Cc: stable@vger.kernel.org # 3.5
Reported-by: Ma Ke <make24@iscas.ac.cn>
Link: https://lore.kernel.org/lkml/20251117013428.21840-1-make24@iscas.ac.cn/
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251218153519.19453-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
lpc32xx_udc_probe() acquires an i2c_client reference through
isp1301_get_client() but fails to release it in both error handling
paths and the normal removal path. This could result in a reference
count leak for the I2C device, preventing proper cleanup and potentially
leading to resource exhaustion. Add put_device() to release the
reference in the probe failure path and in the remove function.
Calling path: isp1301_get_client() -> of_find_i2c_device_by_node() ->
i2c_find_device_by_fwnode(). As comments of i2c_find_device_by_fwnode()
says, 'The user must call put_device(&client->dev) once done with the
i2c client.'
Found by code review.
Cc: stable <stable@kernel.org>
Fixes: 24a28e428351 ("USB: gadget driver for LPC32xx")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Link: https://patch.msgid.link/20251215020931.15324-1-make24@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A recent change fixing a device reference leak in a UDC driver
introduced a potential use-after-free in the non-OF case as the
isp1301_get_client() helper only increases the reference count for the
returned I2C device in the OF case.
Increment the reference count also for non-OF so that the caller can
decrement it unconditionally.
Note that this is inherently racy just as using the returned I2C device
is since nothing is preventing the PHY driver from being unbound while
in use.
Fixes: c84117912bdd ("USB: lpc32xx_udc: Fix error handling in probe")
Cc: stable@vger.kernel.org
Cc: Ma Ke <make24@iscas.ac.cn>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251218153519.19453-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In error paths, call typec_altmode_put_plug() to drop the device reference
obtained by typec_altmode_get_plug().
Fixes: 71ba4fe56656 ("usb: typec: altmodes/displayport: add SOP' support")
Cc: stable <stable@kernel.org>
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://patch.msgid.link/20251206070445.190770-1-lihaoxiang@isrc.iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A recent change fixing a device reference leak introduced a clock
imbalance by reusing an error path so that the clock may be disabled
before having been enabled.
Note that the clock framework allows for passing in NULL clocks so there
is no risk for a NULL pointer dereference.
Also drop the bogus I2C client NULL check added by the offending commit
as the pointer has already been verified to be non-NULL.
Fixes: c84117912bdd ("USB: lpc32xx_udc: Fix error handling in probe")
Cc: stable@vger.kernel.org
Cc: Ma Ke <make24@iscas.ac.cn>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251218153519.19453-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The delayed work item otg_event is initialized in fsl_otg_conf() and
scheduled under two conditions:
1. When a host controller binds to the OTG controller.
2. When the USB ID pin state changes (cable insertion/removal).
A race condition occurs when the device is removed via fsl_otg_remove():
the fsl_otg instance may be freed while the delayed work is still pending
or executing. This leads to use-after-free when the work function
fsl_otg_event() accesses the already freed memory.
The problematic scenario:
(detach thread) | (delayed work)
fsl_otg_remove() |
kfree(fsl_otg_dev) //FREE| fsl_otg_event()
| og = container_of(...) //USE
| og-> //USE
Fix this by calling disable_delayed_work_sync() in fsl_otg_remove()
before deallocating the fsl_otg structure. This ensures the delayed work
is properly canceled and completes execution prior to memory deallocation.
This bug was identified through static analysis.
Fixes: 0807c500a1a6 ("USB: add Freescale USB OTG Transceiver driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://patch.msgid.link/20251205034831.12846-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Originally, the notification for connector change will be enabled after
the first read of the connector status. Therefore, if the event happens
during this window, it will be missing and make the status unsynced.
Get the connector status only after enabling the notification for
connector change to ensure the status is synced.
Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
Cc: stable <stable@kernel.org>
Tested-by: Kenneth R. Crudup <kenny@panix.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hsin-Te Yuan <yuanhsinte@chromium.org>
Link: https://patch.msgid.link/20251218-ucsi-v7-1-aea83e83fb12@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usbhsp_get_pipe() set pipe's flags to IS_USED. In error paths,
usbhsp_put_pipe() is required to clear pipe's flags to prevent
pipe exhaustion.
Fixes: f1407d5c6624 ("usb: renesas_usbhs: Add Renesas USBHS common code")
Cc: stable <stable@kernel.org>
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Link: https://patch.msgid.link/20251204132129.109234-1-haoxiang_li2024@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>