BlackTreeIndependent security intelligenceLinux · Linux
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Canonical’s release and source-package findings are shown separately from local repository availability.
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Ubuntu release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Ubuntu 24.04 LTSnoble · standard archive | linux-raspi-realtime | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical record ↗Source updated 9 Sept 2026 |
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch availableIn the Linux kernel, the following vulnerability has been resolved: ext4: fix ext4_mb_mark_bb() with flex_bg with fast_commit In case of flex_bg feature (which is by default enabled), extents for any given inode might span across blocks from two different block group. ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the starting block group, but it fails to read it again when the extent length boundary overflows to another block group. Then in this below loop it accesses memory beyond the block group bitmap buffer_head and results into a data abort. for (i = 0; i < clen; i++) if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) already++; This patch adds this functionality for checking block group boundary in ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different block group. w/o this patch, I was easily able to hit a data access abort using Power platform. <...> [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters [ 74.533214] EXT4-fs (loop3): shut down requested (2) [ 74.536705] Aborting journal on device loop3-8. [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 sp: c000000015db7300 msr: 800000000280b033 dar: c00000005e980000 dsisr: 40000000 current = 0xc000000027af6880 paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 pid = 5167, comm = mount <...> enter ? for help [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250
In the Linux kernel, the following vulnerability has been resolved: ext4: fix ext4_mb_mark_bb() with flex_bg with fast_commit In case of flex_bg feature (which is by default enabled), extents for any given inode might span across blocks from two different block group. ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the starting block group, but it fails to read it again when the extent length boundary overflows to another block group. Then in this below loop it accesses memory beyond the block group bitmap buffer_head and results into a data abort. for (i = 0; i < clen; i++) if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) already++; This patch adds this functionality for checking block group boundary in ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different block group. w/o this patch, I was easily able to hit a data access abort using Power platform. <...> [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters [ 74.533214] EXT4-fs (loop3): shut down requested (2) [ 74.536705] Aborting journal on device loop3-8. [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 sp: c000000015db7300 msr: 800000000280b033 dar: c00000005e980000 dsisr: 40000000 current = 0xc000000027af6880 paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 pid = 5167, comm = mount <...> enter ? for help [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
In the Linux kernel, the following vulnerability has been resolved: ext4: fix ext4_mb_mark_bb() with flex_bg with fast_commit In case of flex_bg feature (which is by default enabled), extents for any given inode might span across blocks from two different block group. ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the starting block group, but it fails to read it again when the extent length boundary overflows to another block group. Then in this below loop it accesses memory beyond the block group bitmap buffer_head and results into a data abort. for (i = 0; i < clen; i++) if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) already++; This patch adds this functionality for checking block group boundary in ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different block group. w/o this patch, I was easily able to hit a data access abort using Power platform. <...> [ 74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters [ 74.533214] EXT4-fs (loop3): shut down requested (2) [ 74.536705] Aborting journal on device loop3-8. [ 74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 [ 74.703727] Faulting instruction address: 0xc0000000007bffb8 cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060] pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0 lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0 sp: c000000015db7300 msr: 800000000280b033 dar: c00000005e980000 dsisr: 40000000 current = 0xc000000027af6880 paca = 0xc00000003ffd5200 irqmask: 0x03 irq_happened: 0x01 pid = 5167, comm = mount <...> enter ? for help [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
Operational remediation based on structured source evidence.
Published 26 Feb 2025 · Last source change 5 Aug 2026, 08:54 UTC · CWE not yet assigned
Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.