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GFS2: Fix use-after-free bug on umount
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There was a use-after-free with the GFS2 super block during
umount. This patch moves almost all of the umount code from
->put_super into ->kill_sb, the only bit that cannot be moved
being the glock hash clearing which has to remain as ->put_super
due to umount ordering requirements. As a result its now obvious
that the kfree is the final operation, whereas before it was
hidden in ->put_super.

Also gfs2_jindex_free is then only referenced from a single file
so thats moved and marked static too.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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Steven Whitehouse committed Jan 5, 2009
1 parent 2e20470 commit 3af165a
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Showing 6 changed files with 94 additions and 114 deletions.
3 changes: 2 additions & 1 deletion fs/gfs2/glock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1547,8 +1547,9 @@ static void clear_glock(struct gfs2_glock *gl)
* Called when unmounting the filesystem.
*/

void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
void gfs2_gl_hash_clear(struct super_block *sb)
{
struct gfs2_sbd *sdp = sb->s_fs_info;
unsigned long t;
unsigned int x;
int cont;
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2 changes: 1 addition & 1 deletion fs/gfs2/glock.h
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,7 @@ void gfs2_lvb_unhold(struct gfs2_glock *gl);

void gfs2_glock_cb(void *cb_data, unsigned int type, void *data);
void gfs2_reclaim_glock(struct gfs2_sbd *sdp);
void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
void gfs2_gl_hash_clear(struct super_block *sb);
void gfs2_glock_finish_truncate(struct gfs2_inode *ip);

int __init gfs2_glock_init(void);
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98 changes: 88 additions & 10 deletions fs/gfs2/ops_fstype.c
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Original file line number Diff line number Diff line change
Expand Up @@ -705,6 +705,40 @@ static int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
return error;
}

/**
* gfs2_jindex_free - Clear all the journal index information
* @sdp: The GFS2 superblock
*
*/

static void gfs2_jindex_free(struct gfs2_sbd *sdp)
{
struct list_head list, *head;
struct gfs2_jdesc *jd;
struct gfs2_journal_extent *jext;

spin_lock(&sdp->sd_jindex_spin);
list_add(&list, &sdp->sd_jindex_list);
list_del_init(&sdp->sd_jindex_list);
sdp->sd_journals = 0;
spin_unlock(&sdp->sd_jindex_spin);

while (!list_empty(&list)) {
jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
head = &jd->extent_list;
while (!list_empty(head)) {
jext = list_entry(head->next,
struct gfs2_journal_extent,
extent_list);
list_del(&jext->extent_list);
kfree(jext);
}
list_del(&jd->jd_list);
iput(jd->jd_inode);
kfree(jd);
}
}

static int init_journal(struct gfs2_sbd *sdp, int undo)
{
struct inode *master = sdp->sd_master_dir->d_inode;
Expand Down Expand Up @@ -1203,7 +1237,7 @@ static int fill_super(struct super_block *sb, void *data, int silent)
fail_locking:
init_locking(sdp, &mount_gh, UNDO);
fail_lm:
gfs2_gl_hash_clear(sdp);
gfs2_gl_hash_clear(sb);
gfs2_lm_unmount(sdp);
while (invalidate_inodes(sb))
yield();
Expand Down Expand Up @@ -1263,17 +1297,61 @@ static int gfs2_get_sb_meta(struct file_system_type *fs_type, int flags,
static void gfs2_kill_sb(struct super_block *sb)
{
struct gfs2_sbd *sdp = sb->s_fs_info;
if (sdp) {
gfs2_meta_syncfs(sdp);
dput(sdp->sd_root_dir);
dput(sdp->sd_master_dir);
sdp->sd_root_dir = NULL;
sdp->sd_master_dir = NULL;

if (sdp == NULL) {
kill_block_super(sb);
return;
}
shrink_dcache_sb(sb);
gfs2_meta_syncfs(sdp);
dput(sdp->sd_root_dir);
dput(sdp->sd_master_dir);
sdp->sd_root_dir = NULL;
sdp->sd_master_dir = NULL;

/* Unfreeze the filesystem, if we need to */
mutex_lock(&sdp->sd_freeze_lock);
if (sdp->sd_freeze_count)
gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
mutex_unlock(&sdp->sd_freeze_lock);

kthread_stop(sdp->sd_quotad_process);
kthread_stop(sdp->sd_logd_process);
kthread_stop(sdp->sd_recoverd_process);

if (!(sb->s_flags & MS_RDONLY)) {
int error = gfs2_make_fs_ro(sdp);
if (error)
gfs2_io_error(sdp);
}

/* At this point, we're through modifying the disk */
gfs2_jindex_free(sdp);
gfs2_clear_rgrpd(sdp);
iput(sdp->sd_jindex);
iput(sdp->sd_inum_inode);
iput(sdp->sd_statfs_inode);
iput(sdp->sd_rindex);
iput(sdp->sd_quota_inode);

gfs2_glock_put(sdp->sd_rename_gl);
gfs2_glock_put(sdp->sd_trans_gl);

if (!sdp->sd_args.ar_spectator) {
gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
gfs2_glock_dq_uninit(&sdp->sd_ir_gh);
gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
iput(sdp->sd_ir_inode);
iput(sdp->sd_sc_inode);
iput(sdp->sd_qc_inode);
}
gfs2_glock_dq_uninit(&sdp->sd_live_gh);
kill_block_super(sb);
if (sdp)
gfs2_delete_debugfs_file(sdp);
gfs2_lm_unmount(sdp);
gfs2_sys_fs_del(sdp);
gfs2_delete_debugfs_file(sdp);
kfree(sdp);
}

struct file_system_type gfs2_fs_type = {
Expand Down
68 changes: 2 additions & 66 deletions fs/gfs2/ops_super.c
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ static int gfs2_write_inode(struct inode *inode, int sync)
* Returns: errno
*/

static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
{
struct gfs2_holder t_gh;
int error;
Expand All @@ -121,70 +121,6 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
return error;
}

/**
* gfs2_put_super - Unmount the filesystem
* @sb: The VFS superblock
*
*/

static void gfs2_put_super(struct super_block *sb)
{
struct gfs2_sbd *sdp = sb->s_fs_info;
int error;

/* Unfreeze the filesystem, if we need to */

mutex_lock(&sdp->sd_freeze_lock);
if (sdp->sd_freeze_count)
gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
mutex_unlock(&sdp->sd_freeze_lock);

kthread_stop(sdp->sd_quotad_process);
kthread_stop(sdp->sd_logd_process);
kthread_stop(sdp->sd_recoverd_process);

if (!(sb->s_flags & MS_RDONLY)) {
error = gfs2_make_fs_ro(sdp);
if (error)
gfs2_io_error(sdp);
}
/* At this point, we're through modifying the disk */

/* Release stuff */

iput(sdp->sd_jindex);
iput(sdp->sd_inum_inode);
iput(sdp->sd_statfs_inode);
iput(sdp->sd_rindex);
iput(sdp->sd_quota_inode);

gfs2_glock_put(sdp->sd_rename_gl);
gfs2_glock_put(sdp->sd_trans_gl);

if (!sdp->sd_args.ar_spectator) {
gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
gfs2_glock_dq_uninit(&sdp->sd_ir_gh);
gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
iput(sdp->sd_ir_inode);
iput(sdp->sd_sc_inode);
iput(sdp->sd_qc_inode);
}

gfs2_glock_dq_uninit(&sdp->sd_live_gh);
gfs2_clear_rgrpd(sdp);
gfs2_jindex_free(sdp);
/* Take apart glock structures and buffer lists */
gfs2_gl_hash_clear(sdp);
/* Unmount the locking protocol */
gfs2_lm_unmount(sdp);

/* At this point, we're through participating in the lockspace */
gfs2_sys_fs_del(sdp);
kfree(sdp);
}

/**
* gfs2_write_super
* @sb: the superblock
Expand Down Expand Up @@ -686,7 +622,7 @@ const struct super_operations gfs2_super_ops = {
.destroy_inode = gfs2_destroy_inode,
.write_inode = gfs2_write_inode,
.delete_inode = gfs2_delete_inode,
.put_super = gfs2_put_super,
.put_super = gfs2_gl_hash_clear,
.write_super = gfs2_write_super,
.sync_fs = gfs2_sync_fs,
.write_super_lockfs = gfs2_write_super_lockfs,
Expand Down
34 changes: 0 additions & 34 deletions fs/gfs2/super.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,40 +33,6 @@
#include "trans.h"
#include "util.h"

/**
* gfs2_jindex_free - Clear all the journal index information
* @sdp: The GFS2 superblock
*
*/

void gfs2_jindex_free(struct gfs2_sbd *sdp)
{
struct list_head list, *head;
struct gfs2_jdesc *jd;
struct gfs2_journal_extent *jext;

spin_lock(&sdp->sd_jindex_spin);
list_add(&list, &sdp->sd_jindex_list);
list_del_init(&sdp->sd_jindex_list);
sdp->sd_journals = 0;
spin_unlock(&sdp->sd_jindex_spin);

while (!list_empty(&list)) {
jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
head = &jd->extent_list;
while (!list_empty(head)) {
jext = list_entry(head->next,
struct gfs2_journal_extent,
extent_list);
list_del(&jext->extent_list);
kfree(jext);
}
list_del(&jd->jd_list);
iput(jd->jd_inode);
kfree(jd);
}
}

static struct gfs2_jdesc *jdesc_find_i(struct list_head *head, unsigned int jid)
{
struct gfs2_jdesc *jd;
Expand Down
3 changes: 1 addition & 2 deletions fs/gfs2/super.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,15 +25,14 @@ static inline unsigned int gfs2_jindex_size(struct gfs2_sbd *sdp)
return x;
}

void gfs2_jindex_free(struct gfs2_sbd *sdp);

struct gfs2_jdesc *gfs2_jdesc_find(struct gfs2_sbd *sdp, unsigned int jid);
int gfs2_jdesc_check(struct gfs2_jdesc *jd);

int gfs2_lookup_in_master_dir(struct gfs2_sbd *sdp, char *filename,
struct gfs2_inode **ipp);

int gfs2_make_fs_rw(struct gfs2_sbd *sdp);
int gfs2_make_fs_ro(struct gfs2_sbd *sdp);

int gfs2_statfs_init(struct gfs2_sbd *sdp);
void gfs2_statfs_change(struct gfs2_sbd *sdp,
Expand Down

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