CVE-2022-49707
CVE-2022-49707 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.
Key facts
- Severity: Medium (CVSS 3.x base score 5.5)
- EPSS exploit prediction: 0% (19th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2022-54528
- Weakness: CWE-476
- Affected product: Linux Linux Kernel
- Published:
- Last modified:
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: add reserved GDT blocks check We capture a NULL pointer issue when resizing a corrupt ext4 image which is freshly clear resize_inode feature (not run e2fsck). It could be simply reproduced by following steps. The problem is because of the resize_inode feature was cleared, and it will convert the filesystem to meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was not reduced to zero, so could we mistakenly call reserve_backup_gdb() and passing an uninitialized resize_inode to it when adding new group descriptors. mkfs.ext4 /dev/sda 3G tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck mount /dev/sda /mnt resize2fs /dev/sda 8G ======== BUG: kernel NULL pointer dereference, address: 0000000000000028 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748 ... RIP: 0010:ext4_flex_group_add+0xe08/0x2570 ... Call Trace: <TASK> ext4_resize_fs+0xbec/0x1660 __ext4_ioctl+0x1749/0x24e0 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xa6/0x110 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2dd739617b ======== The fix is simple, add a check in ext4_resize_begin() to make sure that the es->s_reserved_gdt_blocks is zero when the resize_inode feature is disabled.
Frequently asked questions
- What is CVE-2022-49707?
- In the Linux kernel, the following vulnerability has been resolved: ext4: add reserved GDT blocks check We capture a NULL pointer issue when resizing a corrupt ext4 image which is freshly clear resize_inode feature (not run e2fsck). It could be simply reproduced by following steps. The problem is because of the resize_inode feature was cleared, and it will convert the filesystem to meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was not reduced to zero, so could we mistakenly call reserve_backup_gdb() and passing an uninitialized resize_inode to it when adding new group descriptors. mkfs.ext4 /dev/sda 3G tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck mount /dev/sda /mnt resize2fs /dev/sda 8G ======== BUG: kernel NULL pointer dereference, address: 0000000000000028 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748 ... RIP: 0010:ext4_flex_group_add+0xe08/0x2570 ... Call Trace: <TASK> ext4_resize_fs+0xbec/0x1660 __ext4_ioctl+0x1749/0x24e0 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xa6/0x110 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2dd739617b ======== The fix is simple, add a check in ext4_resize_begin() to make sure that the es->s_reserved_gdt_blocks is zero when the resize_inode feature is disabled.
- How severe is CVE-2022-49707?
- CVE-2022-49707 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2022-49707 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2022-49707?
- CVE-2022-49707 primarily affects Linux Linux Kernel. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2022-49707?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2022-49707 have an EU (EUVD) identifier?
- Yes. CVE-2022-49707 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2022-54528.
- When was CVE-2022-49707 published?
- CVE-2022-49707 was published on 2025-02-26 and last updated on 2026-06-17.
References
- https://git.kernel.org/stable/c/0dc2fca8e4f9ac4a40e8424a10163369cca0cc06
- https://git.kernel.org/stable/c/33b1bba31f4c784d33d2c2517964bdccdc9204cd
- https://git.kernel.org/stable/c/7c921328ac760bba780bdace41f4cd045f7f1405
- https://git.kernel.org/stable/c/af75c481a2e45e70f62f5942c93695e95bf7bd21
- https://git.kernel.org/stable/c/b55c3cd102a6f48b90e61c44f7f3dda8c290c694
- https://git.kernel.org/stable/c/b9747263b13e5290ac4d63bec47e38f701303cad
- https://git.kernel.org/stable/c/bfd004a1d3a062aac300523d406ac1f3e5f1a82c
- https://git.kernel.org/stable/c/fba54289176702a7caac0b64738406775817f451
Affected products (3)
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.19:rc1:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.19:rc2:*:*:*:*:*:*
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