41 lines
1.5 KiB
Diff
41 lines
1.5 KiB
Diff
From: Theodore Ts'o <tytso@mit.edu>
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Date: Thu, 29 Mar 2018 21:56:09 -0400
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Subject: ext4: fail ext4_iget for root directory if unallocated
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Origin: https://git.kernel.org/linus/8e4b5eae5decd9dfe5a4ee369c22028f90ab4c44
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-1092
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If the root directory has an i_links_count of zero, then when the file
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system is mounted, then when ext4_fill_super() notices the problem and
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tries to call iput() the root directory in the error return path,
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ext4_evict_inode() will try to free the inode on disk, before all of
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the file system structures are set up, and this will result in an OOPS
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caused by a NULL pointer dereference.
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This issue has been assigned CVE-2018-1092.
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https://bugzilla.kernel.org/show_bug.cgi?id=199179
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https://bugzilla.redhat.com/show_bug.cgi?id=1560777
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Reported-by: Wen Xu <wen.xu@gatech.edu>
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Cc: stable@vger.kernel.org
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---
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fs/ext4/inode.c | 6 ++++++
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1 file changed, 6 insertions(+)
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--- a/fs/ext4/inode.c
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+++ b/fs/ext4/inode.c
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@@ -4745,6 +4745,12 @@ struct inode *ext4_iget(struct super_blo
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goto bad_inode;
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raw_inode = ext4_raw_inode(&iloc);
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+ if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) {
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+ EXT4_ERROR_INODE(inode, "root inode unallocated");
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+ ret = -EFSCORRUPTED;
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+ goto bad_inode;
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+ }
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+
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if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
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ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
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if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
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