(Adrian should be CCed on things regarding 2.6.16.y kernel)
On Sun, 23 Sep 2007, Miloslav Semler wrote:
> This patch solves CVE-2007-3104 - sysfs_readdir oops.
> More can be found here:
> http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.22.y.git;a=commit;h=dc351252b33f8fede396d6173dba117bcb933607
>
> Signed-off-by: Miloslav Semler
> ---
> diff -uprN linux-2.6.16.53/fs/sysfs/dir.c linux-2.6.16.53-new/fs/sysfs/dir.c
> --- linux-2.6.16.53/fs/sysfs/dir.c 2007-07-25 23:05:45.000000000 +0200
> +++ linux-2.6.16.53-new/fs/sysfs/dir.c 2007-09-23 18:18:09.000000000 +0200
> @@ -29,6 +29,14 @@ static struct dentry_operations sysfs_de
> .d_iput = sysfs_d_iput,
> };
>
> +static unsigned int sysfs_inode_counter;
> +ino_t sysfs_get_inum(void)
> +{
> + if (unlikely(sysfs_inode_counter < 3))
> + sysfs_inode_counter = 3;
> + return sysfs_inode_counter++;
> +}
> +
> /*
> * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
> */
> @@ -40,8 +48,10 @@ static struct sysfs_dirent * sysfs_new_d
> sd = kmem_cache_alloc(sysfs_dir_cachep, GFP_KERNEL);
> if (!sd)
> return NULL;
> +
>
> memset(sd, 0, sizeof(*sd));
> + sd->s_ino = sysfs_get_inum();
> atomic_set(&sd->s_count, 1);
> INIT_LIST_HEAD(&sd->s_children);
> list_add(&sd->s_sibling, &parent_sd->s_children);
> @@ -385,7 +395,7 @@ static int sysfs_readdir(struct file * f
>
> switch (i) {
> case 0:
> - ino = dentry->d_inode->i_ino;
> + ino = parent_sd->s_ino;
> if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
> break;
> filp->f_pos++;
> @@ -415,10 +425,7 @@ static int sysfs_readdir(struct file * f
>
> name = sysfs_get_name(next);
> len = strlen(name);
> - if (next->s_dentry)
> - ino = next->s_dentry->d_inode->i_ino;
> - else
> - ino = iunique(sysfs_sb, 2);
> + ino = next->s_ino;
>
> if (filldir(dirent, name, len, filp->f_pos,
> ino,
> dt_type(next)) < 0)
> diff -uprN linux-2.6.16.53/fs/sysfs/inode.c
> linux-2.6.16.53-new/fs/sysfs/inode.c
> --- linux-2.6.16.53/fs/sysfs/inode.c 2007-07-25 23:05:45.000000000 +0200
> +++ linux-2.6.16.53-new/fs/sysfs/inode.c 2007-09-23 18:18:09.000000000
> +0200
> @@ -119,6 +119,7 @@ struct inode * sysfs_new_inode(mode_t mo
> inode->i_mapping->a_ops = &sysfs_aops;
> inode->i_mapping->backing_dev_info =
> &sysfs_backing_dev_info;
> inode->i_op = &sysfs_inode_operations;
> + inode->i_ino = sd->s_ino;
>
> if (sd->s_iattr) {
> /* sysfs_dirent has non-default attributes
> diff -uprN linux-2.6.16.53/fs/sysfs/mount.c
> linux-2.6.16.53-new/fs/sysfs/mount.c
> --- linux-2.6.16.53/fs/sysfs/mount.c 2007-07-25 23:05:45.000000000 +0200
> +++ linux-2.6.16.53-new/fs/sysfs/mount.c 2007-09-23 18:18:09.000000000
> +0200
> @@ -29,6 +29,7 @@ static struct sysfs_dirent sysfs_root =
> .s_element = NULL,
> .s_type = SYSFS_ROOT,
> .s_iattr = NULL,
> + .s_ino = 1,
> };
>
> static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
> diff -uprN linux-2.6.16.53/include/linux/sysfs.h
> linux-2.6.16.53-new/include/linux/sysfs.h
> --- linux-2.6.16.53/include/linux/sysfs.h 2007-07-25 23:05:45.000000000
> +0200
> +++ linux-2.6.16.53-new/include/linux/sysfs.h 2007-09-23 18:18:09.000000000
> +0200
> @@ -72,6 +72,7 @@ struct sysfs_dirent {
> void * s_element;
> int s_type;
> umode_t s_mode;
> + ino_t s_ino;
> struct dentry * s_dentry;
> struct iattr * s_iattr;
> };
> -
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