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Btrfs: fix double free of fs root
I got this warning while mounting a btrfs image, [ 3020.509606] ------------[ cut here ]------------ [ 3020.510107] WARNING: CPU: 3 PID: 5581 at lib/idr.c:1051 ida_remove+0xca/0x190 [ 3020.510853] ida_remove called for id=42 which is not allocated. [ 3020.511466] Modules linked in: [ 3020.511802] CPU: 3 PID: 5581 Comm: mount Not tainted 4.7.0-rc5+ #274 [ 3020.512438] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150714_191134- 04/01/2014 [ 3020.513385] 0000000000000286 0000000021295d86 ffff88006c66b8f0 ffffffff8182ba5a [ 3020.514153] 0000000000000000 0000000000000009 ffff88006c66b930 ffffffff810e0ed7 [ 3020.514928] 0000041b00000000 ffffffff8289a8c0 ffff88007f437880 0000000000000000 [ 3020.515717] Call Trace: [ 3020.515965] [<ffffffff8182ba5a>] dump_stack+0xc9/0x13f [ 3020.516487] [<ffffffff810e0ed7>] __warn+0x147/0x160 [ 3020.517005] [<ffffffff810e0f4f>] warn_slowpath_fmt+0x5f/0x80 [ 3020.517572] [<ffffffff8182e6ca>] ida_remove+0xca/0x190 [ 3020.518075] [<ffffffff813a2bcc>] free_anon_bdev+0x2c/0x60 [ 3020.518609] [<ffffffff81657a9f>] free_fs_root+0x13f/0x160 [ 3020.519138] [<ffffffff8165c679>] btrfs_get_fs_root+0x379/0x3d0 [ 3020.519710] [<ffffffff81e6e975>] ? __mutex_unlock_slowpath+0x155/0x2c0 [ 3020.520366] [<ffffffff816615b1>] open_ctree+0x2e91/0x3200 [ 3020.520965] [<ffffffff8161ede2>] btrfs_mount+0x1322/0x15b0 [ 3020.521536] [<ffffffff81e60e74>] ? kmemleak_alloc_percpu+0x44/0x170 [ 3020.522167] [<ffffffff8115f5e1>] ? lockdep_init_map+0x61/0x210 [ 3020.522780] [<ffffffff813a4f59>] mount_fs+0x49/0x2c0 [ 3020.523305] [<ffffffff813d840c>] vfs_kern_mount+0xac/0x1b0 [ 3020.523872] [<ffffffff8161dee1>] btrfs_mount+0x421/0x15b0 [ 3020.524402] [<ffffffff81e60e74>] ? kmemleak_alloc_percpu+0x44/0x170 [ 3020.525045] [<ffffffff8115f5e1>] ? lockdep_init_map+0x61/0x210 [ 3020.525657] [<ffffffff8115f5e1>] ? lockdep_init_map+0x61/0x210 [ 3020.526289] [<ffffffff813a4f59>] mount_fs+0x49/0x2c0 [ 3020.526803] [<ffffffff813d840c>] vfs_kern_mount+0xac/0x1b0 [ 3020.527365] [<ffffffff813dc27a>] do_mount+0x41a/0x1770 [ 3020.527899] [<ffffffff812e800d>] ? strndup_user+0x6d/0xc0 [ 3020.528447] [<ffffffff812e7f68>] ? memdup_user+0x78/0xb0 [ 3020.528987] [<ffffffff813ddad0>] SyS_mount+0x150/0x160 [ 3020.529493] [<ffffffff81e72b7c>] entry_SYSCALL_64_fastpath+0x1f/0xbd It turns out that we free fs root twice, btrfs_init_fs_root() calls free_anon_bdev(root->anon_dev) and later then btrfs_get_fs_root() cals free_fs_root which does another free_anon_bdev() and it ends up with the above warning. Instead of reset root->anon_dev to 0 after free_anon_bdev(), we can let btrfs_init_fs_root() return directly since its callers have already done the free job by calling free_fs_root(). Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Reviewed-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: David Sterba <dsterba@suse.com>
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parent
5e24e9af01
commit
876d2cf141
1 changed files with 3 additions and 9 deletions
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@ -1600,14 +1600,14 @@ int btrfs_init_fs_root(struct btrfs_root *root)
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ret = get_anon_bdev(&root->anon_dev);
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if (ret)
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goto free_writers;
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goto fail;
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mutex_lock(&root->objectid_mutex);
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ret = btrfs_find_highest_objectid(root,
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&root->highest_objectid);
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if (ret) {
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mutex_unlock(&root->objectid_mutex);
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goto free_root_dev;
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goto fail;
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}
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ASSERT(root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);
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@ -1615,14 +1615,8 @@ int btrfs_init_fs_root(struct btrfs_root *root)
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mutex_unlock(&root->objectid_mutex);
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return 0;
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free_root_dev:
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free_anon_bdev(root->anon_dev);
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free_writers:
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btrfs_free_subvolume_writers(root->subv_writers);
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fail:
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kfree(root->free_ino_ctl);
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kfree(root->free_ino_pinned);
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/* the caller is responsible to call free_fs_root */
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return ret;
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}
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