6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Filipe Manana fdmanana@suse.com
[ Upstream commit 7c4e39f9d2af4abaf82ca0e315d1fd340456620f ]
At btrfs_ref_tree_mod() after we successfully inserted the new ref entry (local variable 'ref') into the respective block entry's rbtree (local variable 'be'), if we find an unexpected action of BTRFS_DROP_DELAYED_REF, we error out and free the ref entry without removing it from the block entry's rbtree. Then in the error path of btrfs_ref_tree_mod() we call btrfs_free_ref_cache(), which iterates over all block entries and then calls free_block_entry() for each one, and there we will trigger a use-after-free when we are called against the block entry to which we added the freed ref entry to its rbtree, since the rbtree still points to the block entry, as we didn't remove it from the rbtree before freeing it in the error path at btrfs_ref_tree_mod(). Fix this by removing the new ref entry from the rbtree before freeing it.
Syzbot report this with the following stack traces:
BTRFS error (device loop0 state EA): Ref action 2, root 5, ref_root 0, parent 8564736, owner 0, offset 0, num_refs 18446744073709551615 __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523 update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4314 btrfs_insert_empty_item fs/btrfs/ctree.h:669 [inline] btrfs_insert_orphan_item+0x1f1/0x320 fs/btrfs/orphan.c:23 btrfs_orphan_add+0x6d/0x1a0 fs/btrfs/inode.c:3482 btrfs_unlink+0x267/0x350 fs/btrfs/inode.c:4293 vfs_unlink+0x365/0x650 fs/namei.c:4469 do_unlinkat+0x4ae/0x830 fs/namei.c:4533 __do_sys_unlinkat fs/namei.c:4576 [inline] __se_sys_unlinkat fs/namei.c:4569 [inline] __x64_sys_unlinkat+0xcc/0xf0 fs/namei.c:4569 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f BTRFS error (device loop0 state EA): Ref action 1, root 5, ref_root 5, parent 0, owner 260, offset 0, num_refs 1 __btrfs_mod_ref+0x76b/0xac0 fs/btrfs/extent-tree.c:2521 update_ref_for_cow+0x96a/0x11f0 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411 __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline] __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313 prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586 relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538 BTRFS error (device loop0 state EA): Ref action 2, root 5, ref_root 0, parent 8564736, owner 0, offset 0, num_refs 18446744073709551615 __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523 update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411 __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline] __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313 prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586 relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538 ================================================================== BUG: KASAN: slab-use-after-free in rb_first+0x69/0x70 lib/rbtree.c:473 Read of size 8 at addr ffff888042d1af38 by task syz.0.0/5329
CPU: 0 UID: 0 PID: 5329 Comm: syz.0.0 Not tainted 6.12.0-rc7-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 rb_first+0x69/0x70 lib/rbtree.c:473 free_block_entry+0x78/0x230 fs/btrfs/ref-verify.c:248 btrfs_free_ref_cache+0xa3/0x100 fs/btrfs/ref-verify.c:917 btrfs_ref_tree_mod+0x139f/0x15e0 fs/btrfs/ref-verify.c:898 btrfs_free_extent+0x33c/0x380 fs/btrfs/extent-tree.c:3544 __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523 update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411 __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline] __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313 prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586 relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f996df7e719 RSP: 002b:00007f996ede7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f996e135f80 RCX: 00007f996df7e719 RDX: 0000000020000180 RSI: 00000000c4009420 RDI: 0000000000000004 RBP: 00007f996dff139e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f996e135f80 R15: 00007fff79f32e68 </TASK>
Allocated by task 5329: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:257 [inline] __kmalloc_cache_noprof+0x19c/0x2c0 mm/slub.c:4295 kmalloc_noprof include/linux/slab.h:878 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] btrfs_ref_tree_mod+0x264/0x15e0 fs/btrfs/ref-verify.c:701 btrfs_free_extent+0x33c/0x380 fs/btrfs/extent-tree.c:3544 __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523 update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411 __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline] __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313 prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586 relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 5329: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:2342 [inline] slab_free mm/slub.c:4579 [inline] kfree+0x1a0/0x440 mm/slub.c:4727 btrfs_ref_tree_mod+0x136c/0x15e0 btrfs_free_extent+0x33c/0x380 fs/btrfs/extent-tree.c:3544 __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523 update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512 btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594 btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754 btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116 btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411 __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline] __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313 prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586 relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888042d1af00 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 56 bytes inside of freed 64-byte region [ffff888042d1af00, ffff888042d1af40)
The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x42d1a anon flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000000 ffff88801ac418c0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000200020 00000001f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5055, tgid 5055 (dhcpcd-run-hook), ts 40377240074, free_ts 40376848335 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1541 prep_new_page mm/page_alloc.c:1549 [inline] get_page_from_freelist+0x3649/0x3790 mm/page_alloc.c:3459 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4735 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265 alloc_slab_page+0x6a/0x140 mm/slub.c:2412 allocate_slab+0x5a/0x2f0 mm/slub.c:2578 new_slab mm/slub.c:2631 [inline] ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3818 __slab_alloc+0x58/0xa0 mm/slub.c:3908 __slab_alloc_node mm/slub.c:3961 [inline] slab_alloc_node mm/slub.c:4122 [inline] __do_kmalloc_node mm/slub.c:4263 [inline] __kmalloc_noprof+0x25a/0x400 mm/slub.c:4276 kmalloc_noprof include/linux/slab.h:882 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] tomoyo_encode2 security/tomoyo/realpath.c:45 [inline] tomoyo_encode+0x26f/0x540 security/tomoyo/realpath.c:80 tomoyo_realpath_from_path+0x59e/0x5e0 security/tomoyo/realpath.c:283 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_check_open_permission+0x255/0x500 security/tomoyo/file.c:771 security_file_open+0x777/0x990 security/security.c:3109 do_dentry_open+0x369/0x1460 fs/open.c:945 vfs_open+0x3e/0x330 fs/open.c:1088 do_open fs/namei.c:3774 [inline] path_openat+0x2c84/0x3590 fs/namei.c:3933 page last free pid 5055 tgid 5055 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1112 [inline] free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2642 free_pipe_info+0x300/0x390 fs/pipe.c:860 put_pipe_info fs/pipe.c:719 [inline] pipe_release+0x245/0x320 fs/pipe.c:742 __fput+0x23f/0x880 fs/file_table.c:431 __do_sys_close fs/open.c:1567 [inline] __se_sys_close fs/open.c:1552 [inline] __x64_sys_close+0x7f/0x110 fs/open.c:1552 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address: ffff888042d1ae00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888042d1ae80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
ffff888042d1af00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^ ffff888042d1af80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ffff888042d1b000: 00 00 00 00 00 fc fc 00 00 00 00 00 fc fc 00 00
Reported-by: syzbot+7325f164162e200000c1@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/673723eb.050a0220.1324f8.00a8.GAE@google... Fixes: fd708b81d972 ("Btrfs: add a extent ref verify tool") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/ref-verify.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c index 1ea5bfb8876e4..28ac7995716e0 100644 --- a/fs/btrfs/ref-verify.c +++ b/fs/btrfs/ref-verify.c @@ -849,6 +849,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info, "dropping a ref for a root that doesn't have a ref on the block"); dump_block_entry(fs_info, be); dump_ref_action(fs_info, ra); + rb_erase(&ref->node, &be->refs); kfree(ref); kfree(ra); goto out_unlock;