btrfs: add a sanity check for btrfs root in btrfs_search_slot()
BugLink: https://bugs.launchpad.net/bugs/2101915
[ Upstream commit 3ed51857a50f530ac7a1482e069dfbd1298558d4 ]
Syzbot reports a null-ptr-deref in btrfs_search_slot().
The reproducer is using rescue=ibadroots, and the extent tree root is
corrupted thus the extent tree is NULL.
When scrub tries to search the extent tree to gather the needed extent
info, btrfs_search_slot() doesn't check if the target root is NULL or
not, resulting the null-ptr-deref.
Add sanity check for btrfs root before using it in btrfs_search_slot().
Reported-by: syzbot+3030e17bd57a73d39bd7@syzkaller.appspotmail.com
Fixes: 42437a6386 ("btrfs: introduce mount option rescue=ignorebadroots")
Link: https://syzkaller.appspot.com/bug?extid=3030e17bd57a73d39bd7
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Tested-by: syzbot+3030e17bd57a73d39bd7@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
CVE-2024-56774
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
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@@ -2030,7 +2030,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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const struct btrfs_key *key, struct btrfs_path *p,
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int ins_len, int cow)
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{
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struct btrfs_fs_info *fs_info = root->fs_info;
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struct btrfs_fs_info *fs_info;
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struct extent_buffer *b;
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int slot;
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int ret;
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@@ -2043,6 +2043,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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int min_write_lock_level;
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int prev_cmp;
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if (!root)
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return -EINVAL;
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fs_info = root->fs_info;
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might_sleep();
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lowest_level = p->lowest_level;
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