CVE-2024-53216
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: nfsd: release svc_expkey/svc_export with rcu_work The last reference for `cache_head` can be reduced to zero in `c_show` and `e_show`(using `rcu_read_lock` and `rcu_read_unlock`). Consequently, `svc_export_put` and `expkey_put` will be invoked, leading to two issues: 1. The `svc_export_put` will directly free ex_uuid. However, `e_show`/`c_show` will access `ex_uuid` after `cache_put`, which can trigger a use-after-free issue, shown below. ================================================================== BUG: KASAN: slab-use-after-free in svc_export_show+0x362/0x430 [nfsd] Read of size 1 at addr ff11000010fdc120 by task cat/870 CPU: 1 UID: 0 PID: 870 Comm: cat Not tainted 6.12.0-rc3+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x53/0x70 print_address_description.constprop.0+0x2c/0x3a0 print_report+0xb9/0x280 kasan_report+0xae/0xe0 svc_export_show+0x362/0x430 [nfsd] c_show+0x161/0x390 [sunrpc] seq_read_iter+0x589/0x770 seq_read+0x1e5/0x270 proc_reg_read+0xe1/0x140 vfs_read+0x125/0x530 ksys_read+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e Allocated by task 830: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 __kmalloc_node_track_caller_noprof+0x1bc/0x400 kmemdup_noprof+0x22/0x50 svc_export_parse+0x8a9/0xb80 [nfsd] cache_do_downcall+0x71/0xa0 [sunrpc] cache_write_procfs+0x8e/0xd0 [sunrpc] proc_reg_write+0xe1/0x140 vfs_write+0x1a5/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 868: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x37/0x50 kfree+0xf3/0x3e0 svc_export_put+0x87/0xb0 [nfsd] cache_purge+0x17f/0x1f0 [sunrpc] nfsd_destroy_serv+0x226/0x2d0 [nfsd] nfsd_svc+0x125/0x1e0 [nfsd] write_threads+0x16a/0x2a0 [nfsd] nfsctl_transaction_write+0x74/0xa0 [nfsd] vfs_write+0x1a5/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e 2. We cannot sleep while using `rcu_read_lock`/`rcu_read_unlock`. However, `svc_export_put`/`expkey_put` will call path_put, which subsequently triggers a sleeping operation due to the following `dput`. ============================= WARNING: suspicious RCU usage 5.10.0-dirty #141 Not tainted ----------------------------- ... Call Trace: dump_stack+0x9a/0xd0 ___might_sleep+0x231/0x240 dput+0x39/0x600 path_put+0x1b/0x30 svc_export_put+0x17/0x80 e_show+0x1c9/0x200 seq_read_iter+0x63f/0x7c0 seq_read+0x226/0x2d0 vfs_read+0x113/0x2c0 ksys_read+0xc9/0x170 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x67/0xd1 Fix these issues by using `rcu_work` to help release `svc_expkey`/`svc_export`. This approach allows for an asynchronous context to invoke `path_put` and also facilitates the freeing of `uuid/exp/key` after an RCU grace period.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.1 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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