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CVE-2024-49882— ext4: fix double brelse() the buffer of the extents path

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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ext4文件系统中对extents路径的双重释放问题。

CVSS 7.8 · High EPSS 0.32% · P23

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux ecb94f5fdf4b72547fca022421a9dca1672bddd4< d4574bda63906bf69660e001470bfe1a0ac524ae affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< f9fd47c9d9548f9e47fa60098eab99dde175401d affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< 32bbb59e3f18facd7201bef110010bf35819b8c3 affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< 78bbc3d15b6f443acb26e94418c445bac940d414 affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< 68a69cf60660c73990c1875f94a5551600b04775 affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< 7633407ca4ab8be2916ab214eb44ccebc6a50e1a affected
ecb94f5fdf4b72547fca022421a9dca1672bddd4< 230ee0535d01478bad9a3037292043f39b9be10b affected
… +12 more rows
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I. Basic Information for CVE-2024-49882

Vulnerability Information
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Vulnerability Title
ext4: fix double brelse() the buffer of the extents path
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ext4: fix double brelse() the buffer of the extents path In ext4_ext_try_to_merge_up(), set path[1].p_bh to NULL after it has been released, otherwise it may be released twice. An example of what triggers this is as follows: split2 map split1 |--------|-------|--------| ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_split_convert_extents // path->p_depth == 0 ext4_split_extent // 1. do split1 ext4_split_extent_at |ext4_ext_insert_extent | ext4_ext_create_new_leaf | ext4_ext_grow_indepth | le16_add_cpu(&neh->eh_depth, 1) | ext4_find_extent | // return -ENOMEM |// get error and try zeroout |path = ext4_find_extent | path->p_depth = 1 |ext4_ext_try_to_merge | ext4_ext_try_to_merge_up | path->p_depth = 0 | brelse(path[1].p_bh) ---> not set to NULL here |// zeroout success // 2. update path ext4_find_extent // 3. do split2 ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth le16_add_cpu(&neh->eh_depth, 1) ext4_find_extent path[0].p_bh = NULL; path->p_depth = 1 read_extent_tree_block ---> return err // path[1].p_bh is still the old value ext4_free_ext_path ext4_ext_drop_refs // path->p_depth == 1 brelse(path[1].p_bh) ---> brelse a buffer twice Finally got the following WARRNING when removing the buffer from lru: ============================================ VFS: brelse: Trying to free free buffer WARNING: CPU: 2 PID: 72 at fs/buffer.c:1241 __brelse+0x58/0x90 CPU: 2 PID: 72 Comm: kworker/u19:1 Not tainted 6.9.0-dirty #716 RIP: 0010:__brelse+0x58/0x90 Call Trace: <TASK> __find_get_block+0x6e7/0x810 bdev_getblk+0x2b/0x480 __ext4_get_inode_loc+0x48a/0x1240 ext4_get_inode_loc+0xb2/0x150 ext4_reserve_inode_write+0xb7/0x230 __ext4_mark_inode_dirty+0x144/0x6a0 ext4_ext_insert_extent+0x9c8/0x3230 ext4_ext_map_blocks+0xf45/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] ============================================
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
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ext4文件系统中对extents路径的双重释放问题。
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux ecb94f5fdf4b72547fca022421a9dca1672bddd4 ~ d4574bda63906bf69660e001470bfe1a0ac524ae -
Linux Linux 3.7 -

II. Public POCs for CVE-2024-49882

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III. Intelligence Information for CVE-2024-49882

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Patches & Fixes for CVE-2024-49882 (3)

Same Patch Batch · Linux · 2024-10-21 · 372 CVEs total

CVE-2022-48985 9.8 CRITICAL net: mana: Fix race on per-CQ variable napi work_done
CVE-2024-50033 9.8 CRITICAL slip: make slhc_remember() more robust against malicious packets
CVE-2024-49855 9.8 CRITICAL nbd: fix race between timeout and normal completion
CVE-2022-49003 9.8 CRITICAL nvme: fix SRCU protection of nvme_ns_head list
CVE-2024-50043 9.8 CRITICAL nfsd: fix possible badness in FREE_STATEID
CVE-2024-47695 9.8 CRITICAL RDMA/rtrs-clt: Reset cid to con_num - 1 to stay in bounds
CVE-2024-50047 9.8 CRITICAL smb: client: fix UAF in async decryption
CVE-2024-50046 9.8 CRITICAL NFSv4: Prevent NULL-pointer dereference in nfs42_complete_copies()
CVE-2024-49996 9.4 CRITICAL cifs: Fix buffer overflow when parsing NFS reparse points
CVE-2024-47678 9.4 CRITICAL icmp: change the order of rate limits
CVE-2022-49017 8.8 HIGH tipc: re-fetch skb cb after tipc_msg_validate
CVE-2022-49015 8.8 HIGH net: hsr: Fix potential use-after-free
CVE-2024-49950 8.8 HIGH Bluetooth: L2CAP: Fix uaf in l2cap_connect
CVE-2024-49939 8.8 HIGH wifi: rtw89: avoid to add interface to list twice when SER
CVE-2024-50041 8.8 HIGH i40e: Fix macvlan leak by synchronizing access to mac_filter_hash
CVE-2024-49936 8.8 HIGH net/xen-netback: prevent UAF in xenvif_flush_hash()
CVE-2024-50029 8.8 HIGH Bluetooth: hci_conn: Fix UAF in hci_enhanced_setup_sync
CVE-2024-49930 8.8 HIGH wifi: ath11k: fix array out-of-bound access in SoC stats
CVE-2024-49988 8.8 HIGH ksmbd: add refcnt to ksmbd_conn struct
CVE-2024-49982 8.8 HIGH aoe: fix the potential use-after-free problem in more places

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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