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URL: https://bugzilla.kernel.org/show_bug.cgi?id=199833
Wen Xu 2018-05-26 02:27:26 UTC
The (compressed) crafted image which causes crash
- Overview
Invalid pointer dereference in __del_reloc_root() when mounting a crafted btrfs image
- Reproduce
# mkdir mnt
# mount -t btrfs 82.img mnt
(Reproduced on Linux 4.17-rc5)
- Comment
https://elixir.bootlin.com/linux/v4.17-rc5/source/fs/btrfs/relocation.c#L1324
static void __del_reloc_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct rb_node *rb_node;
struct mapping_node *node = NULL;
struct reloc_control *rc = fs_info->reloc_ctl;
spin_lock(&rc->reloc_root_tree.lock);
rc can be NULL, which means that reloc_ctl may be not initialized
- Kernel message
[ 208.623313] BUG: unable to handle kernel NULL pointer dereference at 0000000000000570
[ 208.624890] PGD 80000001e9495067 P4D 80000001e9495067 PUD 1f0d81067 PMD 0
[ 208.626285] Oops: 0002 [#1] SMP KASAN PTI
[ 208.632054] BTRFS info (device loop0): delayed_refs has NO entry
[ 208.636502] CPU: 1 PID: 1330 Comm: mount Tainted: G B W 4.17.0-rc5+ #6
[ 208.639306] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 208.641177] RIP: 0010:_raw_spin_lock+0x1e/0x40
[ 208.642200] RSP: 0018:ffff8801df437338 EFLAGS: 00010246
[ 208.643240] RAX: 0000000000000000 RBX: 0000000000000570 RCX: 0000000000000000
[ 208.644643] RDX: 0000000000000001 RSI: 0000000000000297 RDI: 0000000000000297
[ 208.646058] RBP: ffff8801df437340 R08: ffffed003ee23ebb R09: ffffed003ee23ebb
[ 208.647464] R10: 0000000000000001 R11: ffffed003ee23eba R12: ffff8801f2e8c400
[ 208.648870] R13: 0000000000000000 R14: ffff8801e3a28000 R15: 0000000000000568
[ 208.650286] FS: 00007fd41a0a7840(0000) GS:ffff8801f7100000(0000) knlGS:0000000000000000
[ 208.651872] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 208.653006] CR2: 0000000000000570 CR3: 00000001e16e6000 CR4: 00000000000006e0
[ 208.654449] Call Trace:
[ 208.654961] __del_reloc_root+0x5a/0x190
[ 208.655755] free_reloc_roots+0x40/0xb0
[ 208.656531] btrfs_recover_relocation+0x2fa/0x750
[ 208.657487] ? btrfs_cleanup_fs_roots+0x351/0x3b0
[ 208.658428] ? btrfs_relocate_block_group+0x370/0x370
[ 208.659433] ? qgroup_reserve+0x650/0x650
[ 208.660237] ? migrate_swap_stop+0x2e0/0x2e0
[ 208.661090] ? btrfs_check_rw_degradable+0xb0/0x240
[ 208.662077] open_ctree+0x37c4/0x3ce9
[ 208.662822] ? close_ctree+0x4a0/0x4a0
[ 208.663580] ? bdi_register_va+0x44/0x50
[ 208.664371] ? super_setup_bdi_name+0x11b/0x1a0
[ 208.665302] ? kill_block_super+0x80/0x80
[ 208.666111] ? snprintf+0x96/0xd0
[ 208.666787] btrfs_mount_root+0xae6/0xc60
[ 208.667596] ? btrfs_mount_root+0xae6/0xc60
[ 208.668449] ? pcpu_block_update_hint_alloc+0x1f5/0x2a0
[ 208.669505] ? btrfs_decode_error+0x40/0x40
[ 208.670345] ? find_next_bit+0x57/0x90
[ 208.671101] ? cpumask_next+0x1a/0x20
[ 208.671837] ? pcpu_alloc+0x449/0x8c0
[ 208.672577] ? pcpu_free_area+0x410/0x410
[ 208.673393] ? memcg_kmem_put_cache+0x1b/0xa0
[ 208.674267] ? memcpy+0x45/0x50
[ 208.674905] mount_fs+0x60/0x1a0
[ 208.675562] ? btrfs_decode_error+0x40/0x40
[ 208.676399] ? mount_fs+0x60/0x1a0
[ 208.677088] ? alloc_vfsmnt+0x309/0x360
[ 208.677880] vfs_kern_mount+0x6b/0x1a0
[ 208.678634] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 208.679671] btrfs_mount+0x209/0xb71
[ 208.680390] ? pcpu_block_update_hint_alloc+0x1f5/0x2a0
[ 208.681442] ? btrfs_remount+0x8e0/0x8e0
[ 208.682247] ? find_next_zero_bit+0x2c/0xa0
[ 208.683119] ? find_next_bit+0x57/0x90
[ 208.683876] ? cpumask_next+0x1a/0x20
[ 208.684619] ? pcpu_alloc+0x449/0x8c0
[ 208.685371] ? pcpu_free_area+0x410/0x410
[ 208.686177] ? memcg_kmem_put_cache+0x1b/0xa0
[ 208.687046] ? memcpy+0x45/0x50
[ 208.687685] mount_fs+0x60/0x1a0
[ 208.688337] ? btrfs_remount+0x8e0/0x8e0
[ 208.689121] ? mount_fs+0x60/0x1a0
[ 208.689828] ? alloc_vfsmnt+0x309/0x360
[ 208.690599] vfs_kern_mount+0x6b/0x1a0
[ 208.691352] do_mount+0x34a/0x18a0
[ 208.692039] ? lockref_put_or_lock+0xcf/0x160
[ 208.692909] ? copy_mount_string+0x20/0x20
[ 208.693742] ? memcg_kmem_put_cache+0x1b/0xa0
[ 208.694615] ? kasan_check_write+0x14/0x20
[ 208.695437] ? _copy_from_user+0x6a/0x90
[ 208.696226] ? memdup_user+0x42/0x60
[ 208.696948] ksys_mount+0x83/0xd0
[ 208.697631] __x64_sys_mount+0x67/0x80
[ 208.698385] do_syscall_64+0x78/0x170
[ 208.699122] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 208.700124] RIP: 0033:0x7fd419987b9a
[ 208.700842] RSP: 002b:00007fff30668b88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
[ 208.702345] RAX: ffffffffffffffda RBX: 0000000001829030 RCX: 00007fd419987b9a
[ 208.703742] RDX: 0000000001829210 RSI: 000000000182af30 RDI: 0000000001831ec0
[ 208.705134] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000014
[ 208.706533] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000000001831ec0
[ 208.707931] R13: 0000000001829210 R14: 0000000000000000 R15: 0000000000000003
[ 208.713050] RIP: _raw_spin_lock+0x1e/0x40 RSP: ffff8801df437338
[ 208.714238] CR2: 0000000000000570
[ 208.714985] ---[ end trace be56bf4112c4e5e3 ]---
Found by Wen Xu and Po-Ning Tseng from SSLab, Gatech.
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