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Linux kernel source tree
ksmbd_alloc_user() copies resp->hash_sz bytes out of the mountd IPC
login response with
user->passkey_sz = resp->hash_sz;
user->passkey = kmalloc(resp->hash_sz, KSMBD_DEFAULT_GFP);
if (user->passkey)
memcpy(user->passkey, resp->hash, resp->hash_sz);
resp->hash_sz is a __u16 supplied by the response, but resp->hash[] is
only KSMBD_REQ_MAX_HASH_SZ bytes. A malformed or malicious login
response can set hash_sz well beyond that (up to 65535), so the memcpy()
reads past the end of the response object. ipc_validate_msg() does not
bound hash_sz, so reject any response whose hash_sz exceeds the on-stack
hash[] buffer before allocating and copying.
[ 2030.238706] BUG: KASAN: slab-out-of-bounds in ksmbd_alloc_user+0x278/0x680
[ 2030.240549] Read of size 65535 at addr ffff888121bb6680 by task kworker/4:1/18611
[ 2030.242296]
[ 2030.242710] CPU: 4 UID: 0 PID: 18611 Comm: kworker/4:1 Not tainted 7.1.0-next-20260623-virtme #96 PREEMPT(lazy)
[ 2030.242732] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 2030.242743] Workqueue: ksmbd-io handle_ksmbd_work
[ 2030.242763] Call Trace:
[ 2030.242769] <TASK>
[ 2030.242776] dump_stack_lvl+0xa2/0xd0
[ 2030.242794] print_address_description+0x77/0x200
[ 2030.242815] ? ksmbd_alloc_user+0x278/0x680
[ 2030.242831] print_report+0x58/0x70
[ 2030.242848] kasan_report+0x117/0x150
[ 2030.242869] ? ksmbd_alloc_user+0x278/0x680
[ 2030.242888] kasan_check_range+0x3c7/0x3f0
[ 2030.242908] ? ksmbd_alloc_user+0x278/0x680
[ 2030.242925] __asan_memcpy+0x29/0x70
[ 2030.242942] ksmbd_alloc_user+0x278/0x680
[ 2030.242960] ksmbd_login_user+0xc3/0x120
[ 2030.242978] ntlm_authenticate+0x5e6/0x1b00
[ 2030.243017] ? __pfx_ntlm_authenticate+0x10/0x10
[ 2030.243035] ? ksmbd_session_lookup+0x188/0x1d0
[ 2030.243054] ? __pfx_ksmbd_session_lookup+0x10/0x10
[ 2030.243090] ? __sanitizer_cov_trace_switch+0x7b/0x140
[ 2030.243108] smb2_sess_setup+0x1e4a/0x27b0
[ 2030.243126] ? copy_from_kernel_nofault+0x199/0x300
[ 2030.243156] ? __pfx_smb2_sess_setup+0x10/0x10
[ 2030.243173] ? get_smb2_cmd_val+0xe3/0x1c0
[ 2030.243208] handle_ksmbd_work+0x954/0x1280
[ 2030.243230] ? __pfx_handle_ksmbd_work+0x10/0x10
[ 2030.243249] ? process_scheduled_works+0xa07/0x1490
[ 2030.243270] ? process_scheduled_works+0xa07/0x1490
[ 2030.243291] process_scheduled_works+0xa70/0x1490
[ 2030.243320] ? __pfx_process_scheduled_works+0x10/0x10
[ 2030.243340] ? do_raw_spin_lock+0x130/0x300
[ 2030.243358] ? lock_is_held_type+0x7b/0x110
[ 2030.243388] worker_thread+0x932/0xe20
[ 2030.243415] kthread+0x38a/0x470
[ 2030.243431] ? __pfx_worker_thread+0x10/0x10
[ 2030.243451] ? __pfx_kthread+0x10/0x10
[ 2030.243467] ret_from_fork+0x484/0x910
[ 2030.243485] ? __pfx_ret_from_fork+0x10/0x10
[ 2030.243501] ? __switch_to+0xc77/0x12c0
[ 2030.243523] ? __pfx_kthread+0x10/0x10
[ 2030.243540] ret_from_fork_asm+0x1a/0x30
[ 2030.243564] </TASK>
[ 2030.243570]
[ 2030.290164] Allocated by task 19279:
[ 2030.290911] kasan_save_track+0x3e/0x80
[ 2030.292179] __kasan_kmalloc+0x72/0x90
[ 2030.293217] __kvmalloc_node_noprof+0x3ff/0x6b0
[ 2030.294467] handle_generic_event+0x59b/0x750
[ 2030.295345] genl_family_rcv_msg_doit+0x238/0x340
[ 2030.296553] genl_rcv_msg+0x606/0x7b0
[ 2030.297129] netlink_rcv_skb+0x22b/0x4a0
[ 2030.298500] genl_rcv+0x2d/0x40
[ 2030.299273] netlink_unicast+0x7ba/0x930
[ 2030.300019] netlink_sendmsg+0x8c3/0xb00
[ 2030.301073] __sock_sendmsg+0xec/0x140
[ 2030.301579] __sys_sendto+0x357/0x470
[ 2030.302255] __x64_sys_sendto+0xe3/0x100
[ 2030.303425] do_syscall_64+0x135/0x460
[ 2030.304763] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 2030.305594]
[ 2030.305819] The buggy address belongs to the object at ffff888121bb6640
[ 2030.305819] which belongs to the cache kmalloc-192 of size 192
[ 2030.309595] The buggy address is located 64 bytes inside of
[ 2030.309595] allocated 166-byte region [ffff888121bb6640, ffff888121bb66e6)
[ 2030.312484]
[ 2030.312719] The buggy address belongs to the physical page:
[ 2030.314315] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121bb6
[ 2030.316481] head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 2030.318248] flags: 0x100000000000040(head|node=0|zone=2)
[ 2030.319662] page_type: f5(slab)
[ 2030.320242] raw: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468
[ 2030.321911] raw: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
[ 2030.324413] head: 0100000000000040 ffff8881000424c0 ffffea00047c1510 ffff888100040468
[ 2030.326150] head: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
[ 2030.327960] head: 0100000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
[ 2030.329615] head: ffff888121bb7ab0 0000000000000000 00000000ffffffff 0000000000000000
[ 2030.331861] page dumped because: kasan: bad access detected
[ 2030.332946]
[ 2030.333502] Memory state around the buggy address:
[ 2030.334698] ffff888121bb6580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2030.336475] ffff888121bb6600: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
[ 2030.338143] >ffff888121bb6680: 00 00 00 00 00 00 00 00 00 00 00 00 06 fc fc fc
[ 2030.339116] ^
[ 2030.341315] ffff888121bb6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2030.342801] ffff888121bb6780: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
[ 2030.344643] ==================================================================
Found with ksmbdzzer [2], a KSMBD fuzzer that drives libFuzzer with a
kcov-dataflow [1] coverage vector: it folds each instrumented
comparison/argument's runtime operand value together with its PC (the
default arm mixes them as pc⊕val) so that a new operand value at a known
site counts as new coverage.
[1] https://lwn.net/Articles/1077606/
[2] https://github.com/yskzalloc/kcov-dataflow
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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