Dmitry Antipov d2a4e4e626 btrfs: fix memory leak in btrfs_do_encoded_write()
Local fuzzing of 6.12.94 has found the following memory leak:

Unreferenced object 0xffff888018050a80 (size 64):
  comm "syz.0.17", pid 10297, jiffies 4294953601
  hex dump (first 32 bytes):
    00 10 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
    10 0a 05 18 80 88 ff ff 10 0a 05 18 80 88 ff ff  ................
  backtrace (crc a8a6fc29):
    kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
    slab_post_alloc_hook mm/slub.c:4152 [inline]
    slab_alloc_node mm/slub.c:4197 [inline]
    __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358
    kmalloc_noprof include/linux/slab.h:878 [inline]
    extent_changeset_alloc fs/btrfs/extent_io.h:207 [inline]
    qgroup_reserve_data+0x1c5/0x7d0 fs/btrfs/qgroup.c:4305
    btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355
    btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746
    btrfs_encoded_write fs/btrfs/file.c:1482 [inline]
    btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507
    btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738
    btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:906 [inline]
    __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892
    do_syscall_x64 arch/x86/entry/common.c:47 [inline]
    do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

Unreferenced object 0xffff888018050a00 (size 64):
  comm "syz.0.17", pid 10297, jiffies 4294953601
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 ff 0f 00 00 00 00 00 00  ................
    90 0a 05 18 80 88 ff ff 90 0a 05 18 80 88 ff ff  ................
  backtrace (crc cb5c9580):
    kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
    slab_post_alloc_hook mm/slub.c:4152 [inline]
    slab_alloc_node mm/slub.c:4197 [inline]
    __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358
    kmalloc_noprof include/linux/slab.h:878 [inline]
    kzalloc_noprof include/linux/slab.h:1014 [inline]
    ulist_prealloc+0x9c/0x110 fs/btrfs/ulist.c:114
    extent_changeset_prealloc fs/btrfs/extent_io.h:217 [inline]
    __set_extent_bit+0x16b/0x1a70 fs/btrfs/extent-io-tree.c:1086
    set_record_extent_bits+0x50/0x90 fs/btrfs/extent-io-tree.c:1821
    qgroup_reserve_data+0x274/0x7d0 fs/btrfs/qgroup.c:4312
    btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355
    btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746
    btrfs_encoded_write fs/btrfs/file.c:1482 [inline]
    btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507
    btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738
    btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:906 [inline]
    __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892
    do_syscall_x64 arch/x86/entry/common.c:47 [inline]
    do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fix this by freeing an extent changeset before returning from
btrfs_do_encoded_write().

Fixes: 7c0c7269f7 ("btrfs: add BTRFS_IOC_ENCODED_WRITE")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-07-31 16:55:11 +02:00
2026-01-26 19:07:09 -08:00
…
2025-02-19 14:53:27 -07:00
2026-06-07 15:37:58 -07:00

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
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* License: See COPYING

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https://www.kernel.org/doc/html/latest/


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============

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* New Kernel Developer - Getting started with kernel development
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* Hardware Vendor - Writing drivers for new hardware
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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
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* 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
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---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
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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
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---------------

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* Driver API Guide: Documentation/driver-api/index.rst
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* 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.


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=========================

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