[PATCH] ubifs: Fix AA deadlock when setting xattr for encrypted file
Zhihao Cheng
chengzhihao1 at huawei.com
Tue Jul 19 01:00:17 PDT 2022
Following process:
vfs_setxattr(host)
ubifs_xattr_set
down_write(host_ui->xattr_sem) <- lock first time
create_xattr
ubifs_new_inode(host)
fscrypt_prepare_new_inode(host)
fscrypt_policy_to_inherit(host)
if (IS_ENCRYPTED(inode))
fscrypt_require_key(host)
fscrypt_get_encryption_info(host)
ubifs_xattr_get(host)
down_read(host_ui->xattr_sem) <- AA deadlock
, which may trigger an AA deadlock problem:
[ 102.620871] INFO: task setfattr:1599 blocked for more than 10 seconds.
[ 102.625298] Not tainted 5.19.0-rc7-00001-gb666b6823ce0-dirty #711
[ 102.628732] task:setfattr state:D stack: 0 pid: 1599
[ 102.628749] Call Trace:
[ 102.628753] <TASK>
[ 102.628776] __schedule+0x482/0x1060
[ 102.629964] schedule+0x92/0x1a0
[ 102.629976] rwsem_down_read_slowpath+0x287/0x8c0
[ 102.629996] down_read+0x84/0x170
[ 102.630585] ubifs_xattr_get+0xd1/0x370 [ubifs]
[ 102.630730] ubifs_crypt_get_context+0x1f/0x30 [ubifs]
[ 102.630791] fscrypt_get_encryption_info+0x7d/0x1c0
[ 102.630810] fscrypt_policy_to_inherit+0x56/0xc0
[ 102.630817] fscrypt_prepare_new_inode+0x35/0x160
[ 102.630830] ubifs_new_inode+0xcc/0x4b0 [ubifs]
[ 102.630873] ubifs_xattr_set+0x591/0x9f0 [ubifs]
[ 102.630961] xattr_set+0x8c/0x3e0 [ubifs]
[ 102.631003] __vfs_setxattr+0x71/0xc0
[ 102.631026] vfs_setxattr+0x105/0x270
[ 102.631034] do_setxattr+0x6d/0x110
[ 102.631041] setxattr+0xa0/0xd0
[ 102.631087] __x64_sys_setxattr+0x2f/0x40
Fetch a reproducer in [Link].
Just like ext4 does, which skips encrypting for inode with
EXT4_EA_INODE_FL flag. Stop encypting xattr inode for ubifs.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216260
Fixes: f4e3634a3b64222 ("ubifs: Fix races between xattr_{set|get} ...")
Fixes: d475a507457b5ca ("ubifs: Add skeleton for fscrypto")
Signed-off-by: Zhihao Cheng <chengzhihao1 at huawei.com>
---
fs/ubifs/dir.c | 25 ++++++++++++++-----------
fs/ubifs/ubifs.h | 2 +-
fs/ubifs/xattr.c | 2 +-
3 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 86151889548e..bc11276301fd 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -68,13 +68,14 @@ static int inherit_flags(const struct inode *dir, umode_t mode)
* @c: UBIFS file-system description object
* @dir: parent directory inode
* @mode: inode mode flags
+ * @is_xattr: whether the inode is xattr inode
*
* This function finds an unused inode number, allocates new inode and
* initializes it. Returns new inode in case of success and an error code in
* case of failure.
*/
struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
- umode_t mode)
+ umode_t mode, bool is_xattr)
{
int err;
struct inode *inode;
@@ -99,10 +100,12 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
current_time(inode);
inode->i_mapping->nrpages = 0;
- err = fscrypt_prepare_new_inode(dir, inode, &encrypted);
- if (err) {
- ubifs_err(c, "fscrypt_prepare_new_inode failed: %i", err);
- goto out_iput;
+ if (!is_xattr) {
+ err = fscrypt_prepare_new_inode(dir, inode, &encrypted);
+ if (err) {
+ ubifs_err(c, "fscrypt_prepare_new_inode failed: %i", err);
+ goto out_iput;
+ }
}
switch (mode & S_IFMT) {
@@ -309,7 +312,7 @@ static int ubifs_create(struct user_namespace *mnt_userns, struct inode *dir,
sz_change = CALC_DENT_SIZE(fname_len(&nm));
- inode = ubifs_new_inode(c, dir, mode);
+ inode = ubifs_new_inode(c, dir, mode, false);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_fname;
@@ -370,7 +373,7 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
if (err)
return ERR_PTR(err);
- inode = ubifs_new_inode(c, dir, mode);
+ inode = ubifs_new_inode(c, dir, mode, false);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_free;
@@ -462,7 +465,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
return err;
}
- inode = ubifs_new_inode(c, dir, mode);
+ inode = ubifs_new_inode(c, dir, mode, false);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_budg;
@@ -1004,7 +1007,7 @@ static int ubifs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
sz_change = CALC_DENT_SIZE(fname_len(&nm));
- inode = ubifs_new_inode(c, dir, S_IFDIR | mode);
+ inode = ubifs_new_inode(c, dir, S_IFDIR | mode, false);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_fname;
@@ -1091,7 +1094,7 @@ static int ubifs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
sz_change = CALC_DENT_SIZE(fname_len(&nm));
- inode = ubifs_new_inode(c, dir, mode);
+ inode = ubifs_new_inode(c, dir, mode, false);
if (IS_ERR(inode)) {
kfree(dev);
err = PTR_ERR(inode);
@@ -1173,7 +1176,7 @@ static int ubifs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
sz_change = CALC_DENT_SIZE(fname_len(&nm));
- inode = ubifs_new_inode(c, dir, S_IFLNK | S_IRWXUGO);
+ inode = ubifs_new_inode(c, dir, S_IFLNK | S_IRWXUGO, false);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_fname;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 7d6d2f152e03..478bbbb5382f 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -2026,7 +2026,7 @@ int ubifs_update_time(struct inode *inode, struct timespec64 *time, int flags);
/* dir.c */
struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
- umode_t mode);
+ umode_t mode, bool is_xattr);
int ubifs_getattr(struct user_namespace *mnt_userns, const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags);
int ubifs_check_dir_empty(struct inode *dir);
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index e4c4761aff7f..3db8486e3725 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -110,7 +110,7 @@ static int create_xattr(struct ubifs_info *c, struct inode *host,
if (err)
return err;
- inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
+ inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO, true);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_budg;
--
2.31.1
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