cbcvebase.
CVE-2024-49882
published 2024-10-21

CVE-2024-49882: 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…

PriorityP337high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.32%
24.4th percentile
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: __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 [...]

Affected

37 ranges· showing 25
VendorProductVersion rangeFixed in
debiandebian_linux
debianlinux< linux 6.1.115-1 (bookworm)linux 6.1.115-1 (bookworm)
debianlinux-6.1< linux 6.1.115-1 (bookworm)linux 6.1.115-1 (bookworm)
linuxlinux
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < d4574bda63906bf69660e001470bfe1a0ac524aed4574bda63906bf69660e001470bfe1a0ac524ae
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < f9fd47c9d9548f9e47fa60098eab99dde175401df9fd47c9d9548f9e47fa60098eab99dde175401d
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2eb6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < 32bbb59e3f18facd7201bef110010bf35819b8c332bbb59e3f18facd7201bef110010bf35819b8c3
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < 78bbc3d15b6f443acb26e94418c445bac940d41478bbc3d15b6f443acb26e94418c445bac940d414
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < 68a69cf60660c73990c1875f94a5551600b0477568a69cf60660c73990c1875f94a5551600b04775
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < 7633407ca4ab8be2916ab214eb44ccebc6a50e1a7633407ca4ab8be2916ab214eb44ccebc6a50e1a
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < 230ee0535d01478bad9a3037292043f39b9be10b230ee0535d01478bad9a3037292043f39b9be10b
linuxlinux>= ecb94f5fdf4b72547fca022421a9dca1672bddd4 < dcaa6c31134c0f515600111c38ed7750003e1b9cdcaa6c31134c0f515600111c38ed7750003e1b9c
linuxlinux_kernel>= 0 < 5.10.234-15.10.234-1
linuxlinux_kernel>= 0 < 6.1.115-16.1.115-1
linuxlinux_kernel>= 0 < 6.11.4-16.11.4-1
linuxlinux_kernel>= 0 < 6.11.4-16.11.4-1
linuxlinux_kernel>= 0 < 5.4.0-208.2285.4.0-208.228
linuxlinux_kernel>= 0 < 5.15.0-127.1375.15.0-127.137
linuxlinux_kernel>= 0 < 6.8.0-54.566.8.0-54.56
linuxlinux_kernel>= 0 < 6.11.0-18.186.11.0-18.18
linuxlinux_kernel>= 3.7 < 4.19.3234.19.323
linuxlinux_kernel>= 4.20 < 5.4.2855.4.285
linuxlinux_kernel>= 5.11 < 5.15.1685.15.168
linuxlinux_kernel>= 5.16 < 6.1.1136.1.113

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv8.8HIGH
vendor_ubuntu8.8HIGH
vendor_debian7.8HIGH
vendor_msrc7.8HIGH
vendor_redhat7.8HIGH
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