Medium · published April 17, 2024
In the Linux kernel, the following vulnerability has been resolved:
quota: Fix potential NULL pointer dereference
Below race may cause NULL pointer dereference
P1 P2
dquot_free_inode quota_off
drop_dquot_ref
remove_dquot_ref
dquots = i_dquot(inode)
dquots = i_dquot(inode)
srcu_read_lock
dquots[cnt]) != NULL (1)
dquots[type] = NULL (2)
spin_lock(&dquots[cnt]->dq_dqb_lock) (3)
....
If dquot_free_inode(or other routines) checks inode's quota pointers (1)
before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer
dereference will be triggered.
So let's fix it by using a temporary pointer to avoid this issue.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | < 4.19.311 | 4.19.311 |
| linux/linux_kernel | ≥ 4.20, < 5.4.273 | 5.4.273 |
| linux/linux_kernel | ≥ 5.5, < 5.10.214 | 5.10.214 |
| linux/linux_kernel | ≥ 5.11, < 5.15.153 | 5.15.153 |
| linux/linux_kernel | ≥ 5.16, < 6.1.83 | 6.1.83 |
| linux/linux_kernel | ≥ 6.2, < 6.6.23 | 6.6.23 |
| linux/linux_kernel | ≥ 6.7, < 6.7.11 | 6.7.11 |
| linux/linux_kernel | ≥ 6.8, < 6.8.2 | 6.8.2 |
| debian/debian_linux | all versions | — |