{"id":"CVE-2024-49882","summary":"ext4: fix double brelse() the buffer of the extents path","details":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix double brelse() the buffer of the extents path\n\nIn ext4_ext_try_to_merge_up(), set path[1].p_bh to NULL after it has been\nreleased, otherwise it may be released twice. An example of what triggers\nthis is as follows:\n\n  split2    map    split1\n|--------|-------|--------|\n\next4_ext_map_blocks\n ext4_ext_handle_unwritten_extents\n  ext4_split_convert_extents\n   // path-\u003ep_depth == 0\n   ext4_split_extent\n     // 1. do split1\n     ext4_split_extent_at\n       |ext4_ext_insert_extent\n       |  ext4_ext_create_new_leaf\n       |    ext4_ext_grow_indepth\n       |      le16_add_cpu(&neh-\u003eeh_depth, 1)\n       |    ext4_find_extent\n       |      // return -ENOMEM\n       |// get error and try zeroout\n       |path = ext4_find_extent\n       |  path-\u003ep_depth = 1\n       |ext4_ext_try_to_merge\n       |  ext4_ext_try_to_merge_up\n       |    path-\u003ep_depth = 0\n       |    brelse(path[1].p_bh)  ---\u003e not set to NULL here\n       |// zeroout success\n     // 2. update path\n     ext4_find_extent\n     // 3. do split2\n     ext4_split_extent_at\n       ext4_ext_insert_extent\n         ext4_ext_create_new_leaf\n           ext4_ext_grow_indepth\n             le16_add_cpu(&neh-\u003eeh_depth, 1)\n           ext4_find_extent\n             path[0].p_bh = NULL;\n             path-\u003ep_depth = 1\n             read_extent_tree_block  ---\u003e return err\n             // path[1].p_bh is still the old value\n             ext4_free_ext_path\n               ext4_ext_drop_refs\n                 // path-\u003ep_depth == 1\n                 brelse(path[1].p_bh)  ---\u003e brelse a buffer twice\n\nFinally got the following WARRNING when removing the buffer from lru:\n\n============================================\nVFS: brelse: Trying to free free buffer\nWARNING: CPU: 2 PID: 72 at fs/buffer.c:1241 __brelse+0x58/0x90\nCPU: 2 PID: 72 Comm: kworker/u19:1 Not tainted 6.9.0-dirty #716\nRIP: 0010:__brelse+0x58/0x90\nCall Trace:\n \u003cTASK\u003e\n __find_get_block+0x6e7/0x810\n bdev_getblk+0x2b/0x480\n __ext4_get_inode_loc+0x48a/0x1240\n ext4_get_inode_loc+0xb2/0x150\n ext4_reserve_inode_write+0xb7/0x230\n __ext4_mark_inode_dirty+0x144/0x6a0\n ext4_ext_insert_extent+0x9c8/0x3230\n ext4_ext_map_blocks+0xf45/0x2dc0\n ext4_map_blocks+0x724/0x1700\n ext4_do_writepages+0x12d6/0x2a70\n[...]\n============================================","modified":"2026-03-20T12:39:25.638897Z","published":"2024-10-21T18:01:20.144Z","related":["MGASA-2024-0344","MGASA-2024-0345","SUSE-SU-2024:3983-1","SUSE-SU-2024:3984-1","SUSE-SU-2024:3985-1","SUSE-SU-2024:3986-1","SUSE-SU-2024:4100-1","SUSE-SU-2024:4318-1","SUSE-SU-2024:4364-1","SUSE-SU-2024:4387-1","SUSE-SU-2025:0034-1","SUSE-SU-2025:20163-1","SUSE-SU-2025:20164-1","SUSE-SU-2025:20246-1","SUSE-SU-2025:20247-1","USN-7276-1","USN-7277-1","openSUSE-SU-2024:14500-1","openSUSE-SU-2025:14705-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/49xxx/CVE-2024-49882.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/230ee0535d01478bad9a3037292043f39b9be10b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/32bbb59e3f18facd7201bef110010bf35819b8c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/68a69cf60660c73990c1875f94a5551600b04775"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7633407ca4ab8be2916ab214eb44ccebc6a50e1a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/78bbc3d15b6f443acb26e94418c445bac940d414"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d4574bda63906bf69660e001470bfe1a0ac524ae"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dcaa6c31134c0f515600111c38ed7750003e1b9c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f9fd47c9d9548f9e47fa60098eab99dde175401d"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/49xxx/CVE-2024-49882.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-49882"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ecb94f5fdf4b72547fca022421a9dca1672bddd4"},{"fixed":"d4574bda63906bf69660e001470bfe1a0ac524ae"},{"fixed":"f9fd47c9d9548f9e47fa60098eab99dde175401d"},{"fixed":"b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e"},{"fixed":"32bbb59e3f18facd7201bef110010bf35819b8c3"},{"fixed":"78bbc3d15b6f443acb26e94418c445bac940d414"},{"fixed":"68a69cf60660c73990c1875f94a5551600b04775"},{"fixed":"7633407ca4ab8be2916ab214eb44ccebc6a50e1a"},{"fixed":"230ee0535d01478bad9a3037292043f39b9be10b"},{"fixed":"dcaa6c31134c0f515600111c38ed7750003e1b9c"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-49882.json"}}],"schema_version":"1.7.5"}