CVE-2022-49850— nilfs2: fix deadlock in nilfs_count_free_blocks()
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I. Basic Information for CVE-2022-49850
Vulnerability Information
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Vulnerability Title
nilfs2: fix deadlock in nilfs_count_free_blocks()
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix deadlock in nilfs_count_free_blocks() A semaphore deadlock can occur if nilfs_get_block() detects metadata corruption while locating data blocks and a superblock writeback occurs at the same time: task 1 task 2 ------ ------ * A file operation * nilfs_truncate() nilfs_get_block() down_read(rwsem A) <-- nilfs_bmap_lookup_contig() ... generic_shutdown_super() nilfs_put_super() * Prepare to write superblock * down_write(rwsem B) <-- nilfs_cleanup_super() * Detect b-tree corruption * nilfs_set_log_cursor() nilfs_bmap_convert_error() nilfs_count_free_blocks() __nilfs_error() down_read(rwsem A) <-- nilfs_set_error() down_write(rwsem B) <-- *** DEADLOCK *** Here, nilfs_get_block() readlocks rwsem A (= NILFS_MDT(dat_inode)->mi_sem) and then calls nilfs_bmap_lookup_contig(), but if it fails due to metadata corruption, __nilfs_error() is called from nilfs_bmap_convert_error() inside the lock section. Since __nilfs_error() calls nilfs_set_error() unless the filesystem is read-only and nilfs_set_error() attempts to writelock rwsem B (= nilfs->ns_sem) to write back superblock exclusively, hierarchical lock acquisition occurs in the order rwsem A -> rwsem B. Now, if another task starts updating the superblock, it may writelock rwsem B during the lock sequence above, and can deadlock trying to readlock rwsem A in nilfs_count_free_blocks(). However, there is actually no need to take rwsem A in nilfs_count_free_blocks() because it, within the lock section, only reads a single integer data on a shared struct with nilfs_sufile_get_ncleansegs(). This has been the case after commit aa474a220180 ("nilfs2: add local variable to cache the number of clean segments"), that is, even before this bug was introduced. So, this resolves the deadlock problem by just not taking the semaphore in nilfs_count_free_blocks().
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于nilfs2文件系统中nilfs_count_free_blocks函数的信号量死锁问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2022-49850
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Same Patch Batch · Linux · 2025-05-01 · 245 CVEs total
| CVE-2022-49854 | mctp: Fix an error handling path in mctp_init() | |
| CVE-2022-49836 | siox: fix possible memory leak in siox_device_add() | |
| CVE-2022-49837 | bpf: Fix memory leaks in __check_func_call | |
| CVE-2022-49838 | sctp: clear out_curr if all frag chunks of current msg are pruned | |
| CVE-2022-49840 | bpf, test_run: Fix alignment problem in bpf_prog_test_run_skb() | |
| CVE-2022-49839 | scsi: scsi_transport_sas: Fix error handling in sas_phy_add() | |
| CVE-2022-49841 | serial: imx: Add missing .thaw_noirq hook | |
| CVE-2022-49842 | ASoC: core: Fix use-after-free in snd_soc_exit() | |
| CVE-2022-49844 | can: dev: fix skb drop check | |
| CVE-2022-49845 | can: j1939: j1939_send_one(): fix missing CAN header initialization | |
| CVE-2022-49846 | udf: Fix a slab-out-of-bounds write bug in udf_find_entry() | |
| CVE-2022-49847 | net: ethernet: ti: am65-cpsw: Fix segmentation fault at module unload | |
| CVE-2022-49849 | btrfs: fix match incorrectly in dev_args_match_device | |
| CVE-2022-49848 | phy: qcom-qmp-combo: fix NULL-deref on runtime resume | |
| CVE-2022-49851 | riscv: fix reserved memory setup | |
| CVE-2022-49852 | riscv: process: fix kernel info leakage | |
| CVE-2022-49862 | tipc: fix the msg->req tlv len check in tipc_nl_compat_name_table_dump_header | |
| CVE-2022-49864 | drm/amdkfd: Fix NULL pointer dereference in svm_migrate_to_ram() | |
| CVE-2022-49865 | ipv6: addrlabel: fix infoleak when sending struct ifaddrlblmsg to network | |
| CVE-2022-49863 | can: af_can: fix NULL pointer dereference in can_rx_register() |
Showing top 20 of 245 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
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Same vendor: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
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