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Commit 9a0467e1 authored by Al Viro's avatar Al Viro Committed by Greg Kroah-Hartman
Browse files

securityfs: fix use-after-free on symlink traversal 



[ Upstream commit 46c874419652bbefdfed17420fd6e88d8a31d9ec ]

symlink body shouldn't be freed without an RCU delay.  Switch securityfs
to ->destroy_inode() and use of call_rcu(); free both the inode and symlink
body in the callback.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 900bf351

security/inode.c

+9 −4
Original line number Diff line number Diff line
@@ -26,17 +26,22 @@ 
static struct vfsmount *mount;

static int mount_count;



static void securityfs_evict_inode(struct inode *inode)

static void securityfs_i_callback(struct rcu_head *head)

{

	truncate_inode_pages_final(&inode->i_data);

	clear_inode(inode);

	struct inode *inode = container_of(head, struct inode, i_rcu);

	if (S_ISLNK(inode->i_mode))

		kfree(inode->i_link);

	free_inode_nonrcu(inode);

}



static void securityfs_destroy_inode(struct inode *inode)

{

	call_rcu(&inode->i_rcu, securityfs_i_callback);

}



static const struct super_operations securityfs_super_operations = {

	.statfs		= simple_statfs,

	.evict_inode	= securityfs_evict_inode,

	.destroy_inode	= securityfs_destroy_inode,

};



static int fill_super(struct super_block *sb, void *data, int silent)