CVE-2025-40119
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: fix potential null deref in ext4_mb_init() In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy() lacks null pointer checking, this leads to a null pointer dereference. ================================================================== EXT4-fs: no memory for groupinfo slab cache BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: Oops: 0002 [#1] SMP PTI CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none) RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40 Call Trace: <TASK> xa_destroy+0x61/0x130 ext4_mb_init+0x483/0x540 __ext4_fill_super+0x116d/0x17b0 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 do_new_mount+0x197/0x300 __x64_sys_mount+0x116/0x150 do_syscall_64+0x50/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy() to prevent this issue. The same fix is also applied to ext4_mb_largest_free_orders_destroy().
How to fix
- Linux Linux08d9175578d6a8e9b81921898fbf01aa669cd2be, 00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae, 3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | d99d714f714c9492dc64d8ab4329b083dbfa9cab ≤ v < 08d9175578d6a8e9b81921898fbf01aa669cd2be, f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e ≤ v < 00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae, f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e ≤ v < 3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188, 6.17 | 08d9175578d6a8e9b81921898fbf01aa669cd2be, 00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae, 3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188 |
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