{"id":"DEBIAN-CVE-2024-49882","details":"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-\u003ep_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-\u003eeh_depth, 1)        |    ext4_find_extent        |      // return -ENOMEM        |// get error and try zeroout        |path = ext4_find_extent        |  path-\u003ep_depth = 1        |ext4_ext_try_to_merge        |  ext4_ext_try_to_merge_up        |    path-\u003ep_depth = 0        |    brelse(path[1].p_bh)  ---\u003e 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-\u003eeh_depth, 1)            ext4_find_extent              path[0].p_bh = NULL;              path-\u003ep_depth = 1              read_extent_tree_block  ---\u003e return err              // path[1].p_bh is still the old value              ext4_free_ext_path                ext4_ext_drop_refs                  // path-\u003ep_depth == 1                  brelse(path[1].p_bh)  ---\u003e 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:  \u003cTASK\u003e  __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 [...] ============================================","modified":"2026-09-15T09:03:12.405320665Z","published":"2024-10-21T18:15:10.790Z","upstream":["CVE-2024-49882"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-49882"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.115-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-49882.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.11.4-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-49882.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.11.4-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-49882.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}