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 * AI Coding Assistant - LLMs and AI-powered development tools 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 AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. 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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The Smatch reported a warning in __ntfs_bitmap_set_bits_in_run():
"warn: passing a valid pointer to 'PTR_ERR'"
This occurs because the 'folio' variable might contain a valid pointer
when jumping to the 'rollback' label, specifically when 'cnt <= 0' is
detected during the subsequent page mapping loop. In such cases,
calling PTR_ERR(folio) is incorrect as it does not contain an error
code.
Fix this by introducing an explicit 'err' variable to track the error
status. This ensures that the rollback logic and the return value
consistently use a proper error code regardless of the state of the
folio pointer.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
When ntfs_attr_get_search_ctx() fails and returns NULL, the function
returned early without calling put_page(ipage).
Fix this by jumping to err_out label on error. The err_out path now
properly releases the page and the mutex, with a NULL check for
the search context.
Reported-by: DaeMyung Kang <charsyam@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
In ntfs_mapping_pairs_decompress(), lowest_vcn is read from
on-disk metadata and used as the initial vcn without validation.
A malformed value can introduce an invalid (e.g. negative) vcn,
corrupting the runlist from the start.
Additionally, the accumulation
vcn += deltaxcn
does not check for s64 overflow. A crafted mapping pairs array
can wrap vcn to a negative value, breaking the monotonically-
increasing invariant relied upon by ntfs_rl_vcn_to_lcn() and
related helpers.
Fix this by validating lowest_vcn and using check_add_overflow()
for vcn accumulation.
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
ntfs_reparse_set_wsl_symlink() converts the symlink target into an
allocated NLS string and transfers ownership to ni->target only after
ntfs_set_ntfs_reparse_data() succeeds. If setting the reparse data fails,
the converted target is left unreferenced and leaks.
Free the converted target on the reparse update failure path. Use kfree()
for the other local failure path as well, matching the ntfs_ucstonls()
allocation contract.
Fixes: fc053f05ca28 ("ntfs: add reparse and ea operations")
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
ntfs_index_walk_down() allocates ictx->ib when descending from the root
into an index allocation block. If that allocation fails, the old code
still passes the NULL buffer to ntfs_ib_read(), which can write through
it via ntfs_inode_attr_pread().
Allocate the index block into a temporary pointer and return -ENOMEM
before changing the index context on allocation failure. Also propagate
ERR_PTR() through ntfs_index_next() and ntfs_readdir() so walk-down
allocation or index block read failures are not mistaken for normal
index iteration inside the filesystem.
ntfs_readdir() keeps the existing userspace-visible behavior of
suppressing readdir errors after marking end_in_iterate; this change only
prevents the walk-down failure path from dereferencing NULL internally.
The failure was reproduced with failslab fail-nth injection on getdents64;
the original module hits a NULL pointer dereference in memcpy_orig through
ntfs_ib_read(), while the patched module reaches the same
ntfs_index_walk_down() allocation failure without crashing.
Fixes: 0a8ac0c1fa0b ("ntfs: update directory operations")
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Pull fbdev fixes from Helge Deller:
- request memory region before use (cobalt_lcdfb, clps711x-fb, hgafb)
- reference cleanups in failure path (offb, savage)
- a spelling fix (atyfb)
* tag 'fbdev-for-7.1-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev:
fbdev: hgafb: Request memory region before ioremap
fbdev: clps711x-fb: Request memory region for MMIO
fbdev: cobalt_lcdfb: Request memory region
fbdev: atyfb: Fix spelling mistake "enfore" -> "enforce"
fbdev: savage: fix probe-path EDID cleanup leaks
fbdev: offb: fix PCI device reference leak on probe failure
Pull ARM updates from Russell King:
- fix a race condition handling PG_dcache_clean
- further cleanups for the fault handling, allowing RT to be enabled
- fixing nzones validation in adfs filesystem driver
- fix for module unwinding
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux:
ARM: 9463/1: Allow to enable RT
ARM: 9472/1: fix race condition on PG_dcache_clean in __sync_icache_dcache()
ARM: 9471/1: module: fix unwind section relocation out of range error
fs/adfs: validate nzones in adfs_validate_bblk()
ARM: provide individual is_translation_fault() and is_permission_fault()
ARM: move FSR fault status definitions before fsr_fs()
ARM: use BIT() and GENMASK() for fault status register fields
ARM: move is_permission_fault() and is_translation_fault() to fault.h
ARM: move vmalloc() lazy-page table population
ARM: ensure interrupts are enabled in __do_user_fault()
The driver calls ioremap() on the HGA video memory at 0xb0000 without
first reserving the physical address range. This leaves the kernel
resource tree incomplete and can cause silent conflicts with other
drivers claiming the same range.
Add a devm_request_mem_region() call before ioremap() in
hga_card_detect() to reserve the memory region.
Signed-off-by: Hardik Phalet <hardik.phalet@pm.me>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>
Pull ring-buffer fix from Steven Rostedt:
- Fix accounting of persistent ring buffer rewind
On boot up, the head page is moved back to the earliest point of the
saved ring buffer. This is because the ring buffer being read by user
space on a crash may not save the part it read. Rewinding the head
page back to the earliest saved position helps keep those events from
being lost.
The number of events is also read during boot up and displayed in the
stats file in the tracefs directory. It's also used for other
accounting as well. On boot up, the "reader page" is accounted for
but a rewind may put it back into the buffer and then the reader page
may be accounted for again.
Save off the original reader page and skip accounting it when
scanning the pages in the ring buffer.
* tag 'trace-ring-buffer-v7.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Do not double count the reader_page
All known issues have been adressed.
Allow to select RT.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Use devm_platform_get_and_ioremap_resource() for resource 0 (the MMIO
control register range) instead of open-coding platform_get_resource()
and devm_ioremap() separately. The helper requests the memory region
before mapping it, which registers the range in /proc/iomem and prevents
another driver from mapping the same registers.
This makes resource 0 consistent with resource 1 (the framebuffer),
which already uses devm_platform_get_and_ioremap_resource().
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Pull block fixes from Jens Axboe:
- Series for zloop, fixing a variety of issues
- t10-pi code cleanup
- Fix for a merge window regression with the bio memory allocation mask
- Fix for a merge window regression in ublk, caused by an issue with
the maple tree iteration code at teardown
- ublk self tests additions
- Zoned device pgmap fixes
- Various little cleanups and fixes
* tag 'block-7.1-20260424' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (21 commits)
Revert "floppy: fix reference leak on platform_device_register() failure"
ublk: avoid unpinning pages under maple tree spinlock
ublk: refactor common helper ublk_shmem_remove_ranges()
ublk: fix maple tree lockdep warning in ublk_buf_cleanup
selftests: ublk: add ublk auto integrity test
selftests: ublk: enable test_integrity_02.sh on fio 3.42
selftests: ublk: remove unused argument to _cleanup
block: only restrict bio allocation gfp mask asked to block
block/blk-throttle: Add WQ_PERCPU to alloc_workqueue users
block: Add WQ_PERCPU to alloc_workqueue users
block: relax pgmap check in bio_add_page for compatible zone device pages
block: add pgmap check to biovec_phys_mergeable
floppy: fix reference leak on platform_device_register() failure
ublk: use unchecked copy helpers for bio page data
t10-pi: reduce ref tag code duplication
zloop: remove irq-safe locking
zloop: factor out zloop_mark_{full,empty} helpers
zloop: set RQF_QUIET when completing requests on deleted devices
zloop: improve the unaligned write pointer warning
zloop: use vfs_truncate
...
Since the cpu_buffer->reader_page is updated if there are unwound
pages. After that update, we should skip the page if it is the
original reader_page, because the original reader_page is already
checked.
Cc: stable@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/177701353063.2223789.1471163147644103306.stgit@mhiramat.tok.corp.google.com
Fixes: ca296d32ece3 ("tracing: ring_buffer: Rewind persistent ring buffer on reboot")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use devm_platform_get_and_ioremap_resource() instead of open-coding
platform_get_resource() and devm_ioremap() separately. The helper
requests the memory region before mapping it, which registers the range
in /proc/iomem and prevents another driver from mapping the same
registers.
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Pull io_uring fixes from Jens Axboe:
- Fix for a NOMMU bug with io_uring, where NOMMU doesn't grab page refs
at mmap time. NOMMU also has entirely broken FOLL_PIN support, yet
here we are
- A few fixes covering minor issues introduced in this merge window
- data race annotation to shut up KCSAN for when io-wq limits are
applied
- A nospec addition for direct descriptor file updating. Rest of the
direct descriptor path already had this, but for some reason the
update did not. Now they are all the same
- Various minor defensive changes that claude identified and suggested
terrible fixes for, turned into actually useful cleanups:
- Use kvfree() for the imu cache. These can come from kmalloc or
vmalloc depending on size, but the in-cache ones are capped
where it's always kmalloc based. Change to kvfree() in the
cleanup path, making future changes unlikely to mess that up
- Negative kbuf consumption lengths. Can't happen right now, but
cqe->res is used directly, which if other codes changes could
then be an error value
- Fix for an issue with the futex code, where partial wakes on a
vectored fuxes would potentially wake the same futex twice, rather
than move on to the next one. This could confuse an application as it
would've expected the next futex to have been woken
- Fix for a bug with ring resizing, where SQEs or CQEs might not have
been copied correctly if large SQEs or CQEs are used in the ring.
Application side issue, where SQEs or CQEs might have been lost
during resize
- Fix for a bug where EPOLL_URING_WAKE might have been lost, causing a
multishot poll to not be terminated when it's nested, like it should
have been
- Fix for an issue with signed comparison of poll references for the
slow path
- Fix for a user struct UAF in the zcrx code
- Two minor zcrx cleanups
* tag 'io_uring-7.1-20260424' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
io_uring: take page references for NOMMU pbuf_ring mmaps
io_uring/poll: ensure EPOLL_ONESHOT is propagated for EPOLL_URING_WAKE
io_uring/zcrx: warn on freelist violations
io_uring/zcrx: clear RQ headers on init
io_uring/zcrx: fix user_struct uaf
io_uring/register: fix ring resizing with mixed/large SQEs/CQEs
io_uring/futex: ensure partial wakes are appropriately dequeued
io_uring/rw: add defensive hardening for negative kbuf lengths
io_uring/rsrc: use kvfree() for the imu cache
io_uring/rsrc: unify nospec indexing for direct descriptors
io_uring: fix spurious fput in registered ring path
io_uring: fix iowq_limits data race in tctx node addition
io_uring/tctx: mark io_wq as exiting before error path teardown
io_uring/tctx: check for setup tctx->io_wq before teardown
io_uring/poll: fix signed comparison in io_poll_get_ownership()
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