Skip to content

Commit

Permalink
ovl: get rid of redundant members in struct ovl_fs
Browse files Browse the repository at this point in the history 
ofs->upper_mnt is copied to ->layers[0].mnt and ->layers[0].trap could be
used instead of a separate ->upperdir_trap.

Split the lowerdir option early to get the number of layers, then allocate
the ->layers array, and finally fill the upper and lower layers, as before.

Get rid of path_put_init() in ovl_lower_dir(), since the only caller will
take care of that.

[Colin Ian King] Fix null pointer dereference on null stack pointer on
error return found by Coverity.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
  • Loading branch information
Miklos Szeredi committed Jun 4, 2020
1 parent 08f4c7c commit b8e42a6
Show file tree
Hide file tree
Showing 2 changed files with 48 additions and 55 deletions.
4 changes: 1 addition & 3 deletions fs/overlayfs/ovl_entry.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,6 @@ struct ovl_path {

/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned int numlayer;
/* Number of unique fs among layers including upper fs */
unsigned int numfs;
Expand All @@ -70,7 +69,6 @@ struct ovl_fs {
bool workdir_locked;
bool share_whiteout;
/* Traps in ovl inode cache */
struct inode *upperdir_trap;
struct inode *workbasedir_trap;
struct inode *workdir_trap;
struct inode *indexdir_trap;
Expand All @@ -84,7 +82,7 @@ struct ovl_fs {

static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
{
return ofs->upper_mnt;
return ofs->layers[0].mnt;
}

static inline struct ovl_fs *OVL_FS(struct super_block *sb)
Expand Down
99 changes: 47 additions & 52 deletions fs/overlayfs/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -216,7 +216,6 @@ static void ovl_free_fs(struct ovl_fs *ofs)
iput(ofs->workbasedir_trap);
iput(ofs->indexdir_trap);
iput(ofs->workdir_trap);
iput(ofs->upperdir_trap);
dput(ofs->whiteout);
dput(ofs->indexdir);
dput(ofs->workdir);
Expand All @@ -225,8 +224,7 @@ static void ovl_free_fs(struct ovl_fs *ofs)
dput(ofs->workbasedir);
if (ofs->upperdir_locked)
ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);
mntput(ofs->upper_mnt);
for (i = 1; i < ofs->numlayer; i++) {
for (i = 0; i < ofs->numlayer; i++) {
iput(ofs->layers[i].trap);
mntput(ofs->layers[i].mnt);
}
Expand Down Expand Up @@ -837,11 +835,11 @@ static int ovl_lower_dir(const char *name, struct path *path,

err = ovl_mount_dir_noesc(name, path);
if (err)
goto out;
return err;

err = ovl_check_namelen(path, ofs, name);
if (err)
goto out_put;
return err;

*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);

Expand All @@ -863,11 +861,6 @@ static int ovl_lower_dir(const char *name, struct path *path,
ofs->xino_mode = -1;

return 0;

out_put:
path_put_init(path);
out:
return err;
}

/* Workdir should not be subdir of upperdir and vice versa */
Expand Down Expand Up @@ -1074,7 +1067,7 @@ static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
}

static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
struct path *upperpath)
struct ovl_layer *upper_layer, struct path *upperpath)
{
struct vfsmount *upper_mnt;
int err;
Expand All @@ -1094,7 +1087,7 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
if (err)
goto out;

err = ovl_setup_trap(sb, upperpath->dentry, &ofs->upperdir_trap,
err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap,
"upperdir");
if (err)
goto out;
Expand All @@ -1108,7 +1101,9 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,

/* Don't inherit atime flags */
upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
ofs->upper_mnt = upper_mnt;
upper_layer->mnt = upper_mnt;
upper_layer->idx = 0;
upper_layer->fsid = 0;

/*
* Inherit SB_NOSEC flag from upperdir.
Expand Down Expand Up @@ -1458,30 +1453,20 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
}

static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
struct path *stack, unsigned int numlower)
struct path *stack, unsigned int numlower,
struct ovl_layer *layers)
{
int err;
unsigned int i;
struct ovl_layer *layers;

err = -ENOMEM;
layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
if (!layers)
goto out;
ofs->layers = layers;

ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL);
if (ofs->fs == NULL)
goto out;

/* idx/fsid 0 are reserved for upper fs even with lower only overlay */
ofs->numfs++;

layers[0].mnt = ovl_upper_mnt(ofs);
layers[0].idx = 0;
layers[0].fsid = 0;
ofs->numlayer = 1;

/*
* All lower layers that share the same fs as upper layer, use the same
* pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower
Expand Down Expand Up @@ -1579,44 +1564,30 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
}

static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
struct ovl_fs *ofs)
const char *lower, unsigned int numlower,
struct ovl_fs *ofs, struct ovl_layer *layers)
{
int err;
char *lowertmp, *lower;
struct path *stack = NULL;
unsigned int stacklen, numlower = 0, i;
unsigned int i;
struct ovl_entry *oe;

err = -ENOMEM;
lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
if (!lowertmp)
goto out_err;

err = -EINVAL;
stacklen = ovl_split_lowerdirs(lowertmp);
if (stacklen > OVL_MAX_STACK) {
pr_err("too many lower directories, limit is %d\n",
OVL_MAX_STACK);
goto out_err;
} else if (!ofs->config.upperdir && stacklen == 1) {
if (!ofs->config.upperdir && numlower == 1) {
pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
goto out_err;
return ERR_PTR(-EINVAL);
} else if (!ofs->config.upperdir && ofs->config.nfs_export &&
ofs->config.redirect_follow) {
pr_warn("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}

err = -ENOMEM;
stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL);
if (!stack)
goto out_err;
return ERR_PTR(-ENOMEM);

err = -EINVAL;
lower = lowertmp;
for (numlower = 0; numlower < stacklen; numlower++) {
err = ovl_lower_dir(lower, &stack[numlower], ofs,
&sb->s_stack_depth);
for (i = 0; i < numlower; i++) {
err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth);
if (err)
goto out_err;

Expand All @@ -1630,7 +1601,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
goto out_err;
}

err = ovl_get_layers(sb, ofs, stack, numlower);
err = ovl_get_layers(sb, ofs, stack, numlower, layers);
if (err)
goto out_err;

Expand All @@ -1648,7 +1619,6 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
for (i = 0; i < numlower; i++)
path_put(&stack[i]);
kfree(stack);
kfree(lowertmp);

return oe;

Expand Down Expand Up @@ -1772,7 +1742,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
struct dentry *root_dentry;
struct ovl_entry *oe;
struct ovl_fs *ofs;
struct ovl_layer *layers;
struct cred *cred;
char *splitlower = NULL;
unsigned int numlower;
int err;

sb->s_d_op = &ovl_dentry_operations;
Expand Down Expand Up @@ -1804,6 +1777,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_err;
}

err = -ENOMEM;
splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
if (!splitlower)
goto out_err;

numlower = ovl_split_lowerdirs(splitlower);
if (numlower > OVL_MAX_STACK) {
pr_err("too many lower directories, limit is %d\n",
OVL_MAX_STACK);
goto out_err;
}

layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
if (!layers)
goto out_err;

ofs->layers = layers;
/* Layer 0 is reserved for upper even if there's no upper */
ofs->numlayer = 1;

sb->s_stack_depth = 0;
sb->s_maxbytes = MAX_LFS_FILESIZE;
atomic_long_set(&ofs->last_ino, 1);
Expand All @@ -1825,7 +1818,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_err;
}

err = ovl_get_upper(sb, ofs, &upperpath);
err = ovl_get_upper(sb, ofs, &layers[0], &upperpath);
if (err)
goto out_err;

Expand All @@ -1840,7 +1833,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
sb->s_time_gran = ovl_upper_mnt(ofs)->mnt_sb->s_time_gran;

}
oe = ovl_get_lowerstack(sb, ofs);
oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers);
err = PTR_ERR(oe);
if (IS_ERR(oe))
goto out_err;
Expand Down Expand Up @@ -1903,6 +1896,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_free_oe;

mntput(upperpath.mnt);
kfree(splitlower);

sb->s_root = root_dentry;

Expand All @@ -1912,6 +1906,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ovl_entry_stack_free(oe);
kfree(oe);
out_err:
kfree(splitlower);
path_put(&upperpath);
ovl_free_fs(ofs);
out:
Expand Down

0 comments on commit b8e42a6

Please sign in to comment.