{"id":"CVE-2024-49880","url":"https://www.cyber-defence.io/tools/cve/CVE-2024-49880","generatedAt":"2026-10-28T05:02:22.720Z","title":"In the Linux kernel, the following vulnerability has been resolved: ext4: fix off by one issue in alloc_flex_gd() Wesley reported an issue: ================================================================== EXT4-fs (dm-5): resizing filesystem from 7168…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix off by one issue in alloc_flex_gd()\n\nWesley reported an issue:\n\n==================================================================\nEXT4-fs (dm-5): resizing filesystem from 7168 to 786432 blocks\n------------[ cut here ]------------\nkernel BUG at fs/ext4/resize.c:324!\nCPU: 9 UID: 0 PID: 3576 Comm: resize2fs Not tainted 6.11.0+ #27\nRIP: 0010:ext4_resize_fs+0x1212/0x12d0\nCall Trace:\n __ext4_ioctl+0x4e0/0x1800\n ext4_ioctl+0x12/0x20\n __x64_sys_ioctl+0x99/0xd0\n x64_sys_call+0x1206/0x20d0\n do_syscall_64+0x72/0x110\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n==================================================================\n\nWhile reviewing the patch, Honza found that when adjusting resize_bg in\nalloc_flex_gd(), it was possible for flex_gd->resize_bg to be bigger than\nflexbg_size.\n\nThe reproduction of the problem requires the following:\n\n o_group = flexbg_size * 2 * n;\n o_size = (o_group + 1) * group_size;\n n_group: [o_group + flexbg_size, o_group + flexbg_size * 2)\n o_size = (n_group + 1) * group_size;\n\nTake n=0,flexbg_size=16 as an example:\n\n              last:15\n|o---------------|--------------n-|\no_group:0    resize to      n_group:30\n\nThe corresponding reproducer is:\n\nimg=test.img\nrm -f $img\ntruncate -s 600M $img\nmkfs.ext4 -F $img -b 1024 -G 16 8M\ndev=`losetup -f --show $img`\nmkdir -p /tmp/test\nmount $dev /tmp/test\nresize2fs $dev 248M\n\nDelete the problematic plus 1 to fix the issue, and add a WARN_ON_ONCE()\nto prevent the issue from happening again.\n\n[ Note: another reproucer which this commit fixes is:\n\n  img=test.img\n  rm -f $img\n  truncate -s 25MiB $img\n  mkfs.ext4 -b 4096 -E nodiscard,lazy_itable_init=0,lazy_journal_init=0 $img\n  truncate -s 3GiB $img\n  dev=`losetup -f --show $img`\n  mkdir -p /tmp/test\n  mount $dev /tmp/test\n  resize2fs $dev 3G\n  umount $dev\n  losetup -d $dev\n\n  -- TYT ]","published":"2024-10-21T18:15:10.000Z","lastModified":"2026-06-17T08:00:39.000Z","status":"Analyzed","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-193"],"affected":["linux/linux kernel"],"epss":{"score":0.00244,"percentile":0.15522,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/0d80d2b8bf613398baf7185009e35f9d0459ecb0","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6121258c2b33ceac3d21f6a221452692c465df88","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/acb559d6826116cc113598640d105094620c2526","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-49880","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}