CVE-2026-23238
Last modified
CVE-2026-23238 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: romfs: check sb_set_blocksize() return value romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). EPSS estimates a 0.19% chance of exploitation in the next 30 days.
Description
In the Linux kernel, the following vulnerability has been resolved: romfs: check sb_set_blocksize() return value romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). Later, when sb_bread() attempts I/O with this oversized block size, it triggers a kernel BUG in folio_set_bh(): kernel BUG at fs/buffer.c:1582! BUG_ON(size > PAGE_SIZE); Fix by checking the return value of sb_set_blocksize() and failing the mount with -EINVAL if it returns 0.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions | Update |
|---|---|---|---|
| Linux | Linux Kernel | >= 2.6.12.1, < 5.10.251 | — |
| Linux | Linux Kernel | >= 5.11, < 5.15.201 | — |
| Linux | Linux Kernel | >= 5.16, < 6.1.164 | — |
| Linux | Linux Kernel | >= 6.2, < 6.6.127 | — |
| Linux | Linux Kernel | >= 6.7, < 6.12.74 | — |
| Linux | Linux Kernel | >= 6.13, < 6.18.13 | — |
| Linux | Linux Kernel | 2.6.12 | — |
| Linux | Linux Kernel | 6.19 | Rc1 |
References
Timeline
- Published
- Last Modified
- Status
- Modified
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