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authorMiklos Szeredi <mszeredi@redhat.com>2020-06-04 10:48:19 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2020-06-04 10:48:19 +0200
commitb8e42a651bdee06202ebdd96cff64fdeabd5b1d6 (patch)
treea3fc302da7b4df46f00c146334d7f6124b6e6a78 /fs/overlayfs
parent08f4c7c86d4cf125389dce9d94423024549f9b02 (diff)
downloadlwn-b8e42a651bdee06202ebdd96cff64fdeabd5b1d6.tar.gz
lwn-b8e42a651bdee06202ebdd96cff64fdeabd5b1d6.zip
ovl: get rid of redundant members in struct ovl_fs
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>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/ovl_entry.h4
-rw-r--r--fs/overlayfs/super.c99
2 files changed, 48 insertions, 55 deletions
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 2da0ff355824..b429c80879ee 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -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;
@@ -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;
@@ -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)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 201be5024494..eb81d8760a6a 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -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);
@@ -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);
}
@@ -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);
@@ -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 */
@@ -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;
@@ -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;
@@ -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.
@@ -1458,18 +1453,13 @@ 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;
@@ -1477,11 +1467,6 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
/* 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
@@ -1579,44 +1564,30 @@ out:
}
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;
@@ -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;
@@ -1648,7 +1619,6 @@ out:
for (i = 0; i < numlower; i++)
path_put(&stack[i]);
kfree(stack);
- kfree(lowertmp);
return oe;
@@ -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;
@@ -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);
@@ -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;
@@ -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;
@@ -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;
@@ -1912,6 +1906,7 @@ out_free_oe:
ovl_entry_stack_free(oe);
kfree(oe);
out_err:
+ kfree(splitlower);
path_put(&upperpath);
ovl_free_fs(ofs);
out: