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

一、漏洞 CVE-2024-49882 基础信息

漏洞标题

Linux ext4文件系统双brelse()漏洞

来源：AIGC 神龙大模型

漏洞描述信息

N/A

来源：AIGC 神龙大模型

CVSS信息

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

来源：AIGC 神龙大模型

漏洞类别

双重释放

来源：AIGC 神龙大模型

漏洞标题

ext4: fix double brelse() the buffer of the extents path

来源：美国国家漏洞数据库 NVD

漏洞描述信息

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 [...] ============================================

来源：美国国家漏洞数据库 NVD

CVSS信息

N/A

来源：美国国家漏洞数据库 NVD

漏洞类别

N/A

来源：美国国家漏洞数据库 NVD

漏洞标题

Linux kernel 安全漏洞

来源：中国国家信息安全漏洞库 CNNVD

漏洞描述信息

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。

来源：中国国家信息安全漏洞库 CNNVD

CVSS信息

N/A

来源：中国国家信息安全漏洞库 CNNVD

漏洞类别

其他

来源：中国国家信息安全漏洞库 CNNVD

二、漏洞 CVE-2024-49882 的公开POC

#	POC 描述	源链接	神龙链接

三、漏洞 CVE-2024-49882 的情报信息

标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
标题： ext4: fix double brelse() the buffer of the extents path - kernel/git/stable/linux.git - Linux kernel stable tree -- 🔗来源链接

标签：
神龙速读
https://nvd.nist.gov/vuln/detail/CVE-2024-49882