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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A use-after-free bug exists in the Tegra ADMA driver when audio streams
are terminated, particularly during XRUN conditions. The issue occurs
when the DMA buffer is freed by tegra_adma_terminate_all() before the
vchan completion tasklet finishes accessing it.
The race condition follows this sequence:
1. DMA transfer completes, triggering an interrupt that schedules the
completion tasklet (tasklet has not executed yet)
2. Audio playback stops, calling tegra_adma_terminate_all() which
frees the DMA buffer memory via kfree()
3. The scheduled tasklet finally executes, calling vchan_complete()
which attempts to access the already-freed memory
Since tasklets can execute at any time after being scheduled, there is
no guarantee that the buffer will remain valid when vchan_complete()
runs.
Fix this by properly synchronizing the virtual channel completion:
- Calling vchan_terminate_vdesc() in tegra_adma_stop() to mark the
descriptors as terminated instead of freeing the descriptor.
- Add the callback tegra_adma_synchronize() that calls
vchan_synchronize() which kills any pending tasklets and frees any
terminated descriptors.
Crash logs:
[ 337.427523] BUG: KASAN: use-after-free in vchan_complete+0x124/0x3b0
[ 337.427544] Read of size 8 at addr ffff000132055428 by task swapper/0/0
[ 337.427562] Call trace:
[ 337.427564] dump_backtrace+0x0/0x320
[ 337.427571] show_stack+0x20/0x30
[ 337.427575] dump_stack_lvl+0x68/0x84
[ 337.427584] print_address_description.constprop.0+0x74/0x2b8
[ 337.427590] kasan_report+0x1f4/0x210
[ 337.427598] __asan_load8+0xa0/0xd0
[ 337.427603] vchan_complete+0x124/0x3b0
[ 337.427609] tasklet_action_common.constprop.0+0x190/0x1d0
[ 337.427617] tasklet_action+0x30/0x40
[ 337.427623] __do_softirq+0x1a0/0x5c4
[ 337.427628] irq_exit+0x110/0x140
[ 337.427633] handle_domain_irq+0xa4/0xe0
[ 337.427640] gic_handle_irq+0x64/0x160
[ 337.427644] call_on_irq_stack+0x20/0x4c
[ 337.427649] do_interrupt_handler+0x7c/0x90
[ 337.427654] el1_interrupt+0x30/0x80
[ 337.427659] el1h_64_irq_handler+0x18/0x30
[ 337.427663] el1h_64_irq+0x7c/0x80
[ 337.427667] cpuidle_enter_state+0xe4/0x540
[ 337.427674] cpuidle_enter+0x54/0x80
[ 337.427679] do_idle+0x2e0/0x380
[ 337.427685] cpu_startup_entry+0x2c/0x70
[ 337.427690] rest_init+0x114/0x130
[ 337.427695] arch_call_rest_init+0x18/0x24
[ 337.427702] start_kernel+0x380/0x3b4
[ 337.427706] __primary_switched+0xc0/0xc8
Fixes: f46b195799b5 ("dmaengine: tegra-adma: Add support for Tegra210 ADMA")
Signed-off-by: Sheetal <sheetal@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20251110142445.3842036-1-sheetal@nvidia.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
When fsl_edma_alloc_chan_resources() fails after clk_prepare_enable(),
the error paths only free IRQs and destroy the TCD pool, but forget to
call clk_disable_unprepare(). This causes the channel clock to remain
enabled, leaking power and resources.
Fix it by disabling the channel clock in the error unwind path.
Fixes: d8d4355861d8 ("dmaengine: fsl-edma: add i.MX8ULP edma support")
Cc: stable@vger.kernel.org
Suggested-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20251014090522.827726-1-zhen.ni@easystack.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Add proper locking in mmp_pdma_residue() to prevent use-after-free when
accessing descriptor list and descriptor contents.
The race occurs when multiple threads call tx_status() while the tasklet
on another CPU is freeing completed descriptors:
CPU 0 CPU 1
----- -----
mmp_pdma_tx_status()
mmp_pdma_residue()
-> NO LOCK held
list_for_each_entry(sw, ..)
DMA interrupt
dma_do_tasklet()
-> spin_lock(&desc_lock)
list_move(sw->node, ...)
spin_unlock(&desc_lock)
| dma_pool_free(sw) <- FREED!
-> access sw->desc <- UAF!
This issue can be reproduced when running dmatest on the same channel with
multiple threads (threads_per_chan > 1).
Fix by protecting the chain_running list iteration and descriptor access
with the chan->desc_lock spinlock.
Signed-off-by: Juan Li <lijuan@linux.spacemit.com>
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Link: https://patch.msgid.link/20251216-mmp-pdma-race-v1-1-976a224bb622@riscstar.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the UDMA platform
device.
Note that holding a reference to a platform device does not prevent its
driver data from going away so there is no point in keeping the
reference after the lookup helper returns.
Fixes: d70241913413 ("dmaengine: ti: k3-udma: Add glue layer for non DMAengine users")
Fixes: 1438cde8fe9c ("dmaengine: ti: k3-udma: add missing put_device() call in of_xudma_dev_get()")
Cc: stable@vger.kernel.org # 5.6: 1438cde8fe9c
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-17-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Use a common exit path to drop the cross platform device reference on
errors for consistency with am335x.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-16-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the crossbar
platform device during am335x route allocation.
Fixes: 42dbdcc6bf96 ("dmaengine: ti-dma-crossbar: Add support for crossbar on AM33xx/AM43xx")
Cc: stable@vger.kernel.org # 4.4
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-15-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the crossbar
platform device during dra7x route allocation.
Note that commit 615a4bfc426e ("dmaengine: ti: Add missing put_device in
ti_dra7_xbar_route_allocate") fixed the leak in the error paths but the
reference is still leaking on successful allocation.
Fixes: a074ae38f859 ("dmaengine: Add driver for TI DMA crossbar on DRA7x")
Fixes: 615a4bfc426e ("dmaengine: ti: Add missing put_device in ti_dra7_xbar_route_allocate")
Cc: stable@vger.kernel.org # 4.2: 615a4bfc426e
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-14-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Error labels should be named after what they do (and not after wherefrom
they are jumped to).
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://patch.msgid.link/20251117161258.10679-13-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken to the DMA master OF node also on
late route allocation failures.
Fixes: df7e762db5f6 ("dmaengine: Add STM32 DMAMUX driver")
Cc: stable@vger.kernel.org # 4.15
Cc: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://patch.msgid.link/20251117161258.10679-12-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the DMA mux
platform device during route allocation.
Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.
Fixes: df7e762db5f6 ("dmaengine: Add STM32 DMAMUX driver")
Cc: stable@vger.kernel.org # 4.15
Cc: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://patch.msgid.link/20251117161258.10679-11-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the ICU device
during probe also on probe failures (e.g. probe deferral).
Fixes: 7de873201c44 ("dmaengine: sh: rz-dmac: Add RZ/V2H(P) support")
Cc: stable@vger.kernel.org # 6.16
Cc: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Link: https://patch.msgid.link/20251117161258.10679-10-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the DMA mux
platform device during route allocation.
Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.
Fixes: 5d318b595982 ("dmaengine: Add dma router for pl08x in LPC32XX SoC")
Cc: stable@vger.kernel.org # 6.12
Cc: Piotr Wojtaszczyk <piotr.wojtaszczyk@timesys.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251117161258.10679-9-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the DMA mux
platform device during route allocation.
Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.
Fixes: e5f4ae84be74 ("dmaengine: add driver for lpc18xx dmamux")
Cc: stable@vger.kernel.org # 4.3
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Link: https://patch.msgid.link/20251117161258.10679-8-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the idxd device as
part of the compat bind and unbind sysfs interface.
Fixes: 6e7f3ee97bbe ("dmaengine: idxd: move dsa_drv support to compatible mode")
Cc: stable@vger.kernel.org # 5.15
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-7-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken to the DMA master OF node also on
late route allocation failures.
Fixes: 134d9c52fca2 ("dmaengine: dw: dmamux: Introduce RZN1 DMA router support")
Cc: stable@vger.kernel.org # 5.19
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20251117161258.10679-6-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Make sure to drop the reference taken when looking up the DMA mux
platform device during route allocation.
Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.
Fixes: db7d07b5add4 ("dmaengine: add driver for Sophgo CV18XX/SG200X dmamux")
Cc: stable@vger.kernel.org # 6.17
Cc: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-5-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>