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Commit e91cce02 authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Greg Kroah-Hartman
Browse files

ext4: add more paranoia checking in ext4_expand_extra_isize handling 

commit 4ea99936a1630f51fc3a2d61a58ec4a1c4b7d55a upstream.

It's possible to specify a non-zero s_want_extra_isize via debugging
option, and this can cause bad things(tm) to happen when using a file
system with an inode size of 128 bytes.

Add better checking when the file system is mounted, as well as when
we are actually doing the trying to do the inode expansion.

Link: https://lore.kernel.org/r/20191110121510.GH23325@mit.edu


Reported-by: default avatar <syzbot+f8d6f8386ceacdbfff57@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+33d7ea72e47de3bdf4e1@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+44b6763edfc17144296f@syzkaller.appspotmail.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 10d3899d

fs/ext4/inode.c

+15 −0
Original line number Diff line number Diff line
@@ -5904,8 +5904,23 @@ static int __ext4_expand_extra_isize(struct inode *inode, 
{

	struct ext4_inode *raw_inode;

	struct ext4_xattr_ibody_header *header;

	unsigned int inode_size = EXT4_INODE_SIZE(inode->i_sb);

	struct ext4_inode_info *ei = EXT4_I(inode);

	int error;



	/* this was checked at iget time, but double check for good measure */

	if ((EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > inode_size) ||

	    (ei->i_extra_isize & 3)) {

		EXT4_ERROR_INODE(inode, "bad extra_isize %u (inode size %u)",

				 ei->i_extra_isize,

				 EXT4_INODE_SIZE(inode->i_sb));

		return -EFSCORRUPTED;

	}

	if ((new_extra_isize < ei->i_extra_isize) ||

	    (new_extra_isize < 4) ||

	    (new_extra_isize > inode_size - EXT4_GOOD_OLD_INODE_SIZE))

		return -EINVAL;	/* Should never happen */



	raw_inode = ext4_raw_inode(iloc);



	header = IHDR(inode, raw_inode);

fs/ext4/super.c

+12 −9
Original line number Diff line number Diff line
@@ -3517,12 +3517,15 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb) 
{

	struct ext4_sb_info *sbi = EXT4_SB(sb);

	struct ext4_super_block *es = sbi->s_es;



	/* determine the minimum size of new large inodes, if present */

	if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE &&

	    sbi->s_want_extra_isize == 0) {

		sbi->s_want_extra_isize = sizeof(struct ext4_inode) -

	unsigned def_extra_isize = sizeof(struct ext4_inode) -

						EXT4_GOOD_OLD_INODE_SIZE;



	if (sbi->s_inode_size == EXT4_GOOD_OLD_INODE_SIZE) {

		sbi->s_want_extra_isize = 0;

		return;

	}

	if (sbi->s_want_extra_isize < 4) {

		sbi->s_want_extra_isize = def_extra_isize;

		if (ext4_has_feature_extra_isize(sb)) {

			if (sbi->s_want_extra_isize <

			    le16_to_cpu(es->s_want_extra_isize))
@@ -3535,10 +3538,10 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb) 
		}

	}

	/* Check if enough inode space is available */

	if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >

							sbi->s_inode_size) {

		sbi->s_want_extra_isize = sizeof(struct ext4_inode) -

						       EXT4_GOOD_OLD_INODE_SIZE;

	if ((sbi->s_want_extra_isize > sbi->s_inode_size) ||

	    (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >

							sbi->s_inode_size)) {

		sbi->s_want_extra_isize = def_extra_isize;

		ext4_msg(sb, KERN_INFO,

			 "required extra inode space not available");

	}