CVE-2022-49282

In the Linux kernel, the following vulnerability has been resolved:

f2fs: quota: fix loop condition at f2fs_quota_sync()

cnt should be passed to sb_has_quota_active() instead of type to check active quota properly.

Moreover, when the type is -1, the compiler with enough inline knowledge can discard sb_has_quota_active() check altogether, causing a NULL pointer dereference at the following inode_lock(dqopt->files[cnt]):

[ 2.796010] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a0 [ 2.796024] Mem abort info: [ 2.796025] ESR = 0x96000005 [ 2.796028] EC = 0x25: DABT (current EL), IL = 32 bits [ 2.796029] SET = 0, FnV = 0 [ 2.796031] EA = 0, S1PTW = 0 [ 2.796032] Data abort info: [ 2.796034] ISV = 0, ISS = 0x00000005 [ 2.796035] CM = 0, WnR = 0 [ 2.796046] user pgtable: 4k pages, 39-bit VAs, pgdp=00000003370d1000 [ 2.796048] [00000000000000a0] pgd=0000000000000000, pud=0000000000000000 [ 2.796051] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 2.796056] CPU: 7 PID: 640 Comm: f2fs_ckpt-259:7 Tainted: G S 5.4.179-arter97-r8-64666-g2f16e087f9d8 #1 [ 2.796057] Hardware name: Qualcomm Technologies, Inc. Lahaina MTP lemonadep (DT) [ 2.796059] pstate: 80c00005 (Nzcv daif +PAN +UAO) [ 2.796065] pc : down_write+0x28/0x70 [ 2.796070] lr : f2fs_quota_sync+0x100/0x294 [ 2.796071] sp : ffffffa3f48ffc30 [ 2.796073] x29: ffffffa3f48ffc30 x28: 0000000000000000 [ 2.796075] x27: ffffffa3f6d718b8 x26: ffffffa415fe9d80 [ 2.796077] x25: ffffffa3f7290048 x24: 0000000000000001 [ 2.796078] x23: 0000000000000000 x22: ffffffa3f7290000 [ 2.796080] x21: ffffffa3f72904a0 x20: ffffffa3f7290110 [ 2.796081] x19: ffffffa3f77a9800 x18: ffffffc020aae038 [ 2.796083] x17: ffffffa40e38e040 x16: ffffffa40e38e6d0 [ 2.796085] x15: ffffffa40e38e6cc x14: ffffffa40e38e6d0 [ 2.796086] x13: 00000000000004f6 x12: 00162c44ff493000 [ 2.796088] x11: 0000000000000400 x10: ffffffa40e38c948 [ 2.796090] x9 : 0000000000000000 x8 : 00000000000000a0 [ 2.796091] x7 : 0000000000000000 x6 : 0000d1060f00002a [ 2.796093] x5 : ffffffa3f48ff718 x4 : 000000000000000d [ 2.796094] x3 : 00000000060c0000 x2 : 0000000000000001 [ 2.796096] x1 : 0000000000000000 x0 : 00000000000000a0 [ 2.796098] Call trace: [ 2.796100] down_write+0x28/0x70 [ 2.796102] f2fs_quota_sync+0x100/0x294 [ 2.796104] block_operations+0x120/0x204 [ 2.796106] f2fs_write_checkpoint+0x11c/0x520 [ 2.796107] __checkpoint_and_complete_reqs+0x7c/0xd34 [ 2.796109] issue_checkpoint_thread+0x6c/0xb8 [ 2.796112] kthread+0x138/0x414 [ 2.796114] ret_from_fork+0x10/0x18 [ 2.796117] Code: aa0803e0 aa1f03e1 52800022 aa0103e9 (c8e97d02) [ 2.796120] —[ end trace 96e942e8eb6a0b53 ]— [ 2.800116] Kernel panic - not syncing: Fatal exception [ 2.800120] SMP: stopping secondary CPUs

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/680af5b824a52faa819167628665804a14f0e0df
• https://git.kernel.org/stable/c/724469814d805820cd37ea789769dba94123ff1a
• https://git.kernel.org/stable/c/e58ee6bd939b773675240f5d0f5b88a367c037c4
• https://git.kernel.org/stable/c/e9ebf1e8fc50b6a9336f9aea1082d7845e568d0e
• https://git.kernel.org/stable/c/f1d5946d47c0827bae39e1537959ce8d6f0224c5
• https://git.kernel.org/stable/c/f9156db0987f1b426015d56505e2c58dee70c90d