The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From f4e3634a3b642225a530c292fdb1e8a4007507f5 Mon Sep 17 00:00:00 2001
From: Zhihao Cheng chengzhihao1@huawei.com Date: Mon, 31 May 2021 20:52:09 +0800 Subject: [PATCH] ubifs: Fix races between xattr_{set|get} and listxattr operations
UBIFS may occur some problems with concurrent xattr_{set|get} and listxattr operations, such as assertion failure, memory corruption, stale xattr value[1].
Fix it by importing a new rw-lock in @ubifs_inode to serilize write operations on xattr, concurrent read operations are still effective, just like ext4.
[1] https://lore.kernel.org/linux-mtd/20200630130438.141649-1-houtao1@huawei.com
Fixes: 1e51764a3c2ac05a23 ("UBIFS: add new flash file system") Cc: stable@vger.kernel.org # v2.6+ Signed-off-by: Zhihao Cheng chengzhihao1@huawei.com Reviewed-by: Sascha Hauer s.hauer@pengutronix.de Signed-off-by: Richard Weinberger richard@nod.at
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 7b572e1414ba..e279a069a26b 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -275,6 +275,7 @@ static struct inode *ubifs_alloc_inode(struct super_block *sb) memset((void *)ui + sizeof(struct inode), 0, sizeof(struct ubifs_inode) - sizeof(struct inode)); mutex_init(&ui->ui_mutex); + init_rwsem(&ui->xattr_sem); spin_lock_init(&ui->ui_lock); return &ui->vfs_inode; }; diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h index b65c599a386a..7e978f421430 100644 --- a/fs/ubifs/ubifs.h +++ b/fs/ubifs/ubifs.h @@ -356,6 +356,7 @@ struct ubifs_gced_idx_leb { * @ui_mutex: serializes inode write-back with the rest of VFS operations, * serializes "clean <-> dirty" state changes, serializes bulk-read, * protects @dirty, @bulk_read, @ui_size, and @xattr_size + * @xattr_sem: serilizes write operations (remove|set|create) on xattr * @ui_lock: protects @synced_i_size * @synced_i_size: synchronized size of inode, i.e. the value of inode size * currently stored on the flash; used only for regular file @@ -409,6 +410,7 @@ struct ubifs_inode { unsigned int bulk_read:1; unsigned int compr_type:2; struct mutex ui_mutex; + struct rw_semaphore xattr_sem; spinlock_t ui_lock; loff_t synced_i_size; loff_t ui_size; diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c index 6b1e9830b274..1fce27e9b769 100644 --- a/fs/ubifs/xattr.c +++ b/fs/ubifs/xattr.c @@ -285,6 +285,7 @@ int ubifs_xattr_set(struct inode *host, const char *name, const void *value, if (!xent) return -ENOMEM;
+ down_write(&ubifs_inode(host)->xattr_sem); /* * The extended attribute entries are stored in LNC, so multiple * look-ups do not involve reading the flash. @@ -319,6 +320,7 @@ int ubifs_xattr_set(struct inode *host, const char *name, const void *value, iput(inode);
out_free: + up_write(&ubifs_inode(host)->xattr_sem); kfree(xent); return err; } @@ -341,18 +343,19 @@ ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf, if (!xent) return -ENOMEM;
+ down_read(&ubifs_inode(host)->xattr_sem); xent_key_init(c, &key, host->i_ino, &nm); err = ubifs_tnc_lookup_nm(c, &key, xent, &nm); if (err) { if (err == -ENOENT) err = -ENODATA; - goto out_unlock; + goto out_cleanup; }
inode = iget_xattr(c, le64_to_cpu(xent->inum)); if (IS_ERR(inode)) { err = PTR_ERR(inode); - goto out_unlock; + goto out_cleanup; }
ui = ubifs_inode(inode); @@ -374,7 +377,8 @@ ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf, out_iput: mutex_unlock(&ui->ui_mutex); iput(inode); -out_unlock: +out_cleanup: + up_read(&ubifs_inode(host)->xattr_sem); kfree(xent); return err; } @@ -406,16 +410,21 @@ ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size) dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino, dentry, size);
+ down_read(&host_ui->xattr_sem); len = host_ui->xattr_names + host_ui->xattr_cnt; - if (!buffer) + if (!buffer) { /* * We should return the minimum buffer size which will fit a * null-terminated list of all the extended attribute names. */ - return len; + err = len; + goto out_err; + }
- if (len > size) - return -ERANGE; + if (len > size) { + err = -ERANGE; + goto out_err; + }
lowest_xent_key(c, &key, host->i_ino); while (1) { @@ -437,8 +446,9 @@ ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size) pxent = xent; key_read(c, &xent->key, &key); } - kfree(pxent); + up_read(&host_ui->xattr_sem); + if (err != -ENOENT) { ubifs_err(c, "cannot find next direntry, error %d", err); return err; @@ -446,6 +456,10 @@ ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
ubifs_assert(c, written <= size); return written; + +out_err: + up_read(&host_ui->xattr_sem); + return err; }
static int remove_xattr(struct ubifs_info *c, struct inode *host, @@ -504,6 +518,7 @@ int ubifs_purge_xattrs(struct inode *host) ubifs_warn(c, "inode %lu has too many xattrs, doing a non-atomic deletion", host->i_ino);
+ down_write(&ubifs_inode(host)->xattr_sem); lowest_xent_key(c, &key, host->i_ino); while (1) { xent = ubifs_tnc_next_ent(c, &key, &nm); @@ -523,7 +538,7 @@ int ubifs_purge_xattrs(struct inode *host) ubifs_ro_mode(c, err); kfree(pxent); kfree(xent); - return err; + goto out_err; }
ubifs_assert(c, ubifs_inode(xino)->xattr); @@ -535,7 +550,7 @@ int ubifs_purge_xattrs(struct inode *host) kfree(xent); iput(xino); ubifs_err(c, "cannot remove xattr, error %d", err); - return err; + goto out_err; }
iput(xino); @@ -544,14 +559,19 @@ int ubifs_purge_xattrs(struct inode *host) pxent = xent; key_read(c, &xent->key, &key); } - kfree(pxent); + up_write(&ubifs_inode(host)->xattr_sem); + if (err != -ENOENT) { ubifs_err(c, "cannot find next direntry, error %d", err); return err; }
return 0; + +out_err: + up_write(&ubifs_inode(host)->xattr_sem); + return err; }
/** @@ -594,6 +614,7 @@ static int ubifs_xattr_remove(struct inode *host, const char *name) if (!xent) return -ENOMEM;
+ down_write(&ubifs_inode(host)->xattr_sem); xent_key_init(c, &key, host->i_ino, &nm); err = ubifs_tnc_lookup_nm(c, &key, xent, &nm); if (err) { @@ -618,6 +639,7 @@ static int ubifs_xattr_remove(struct inode *host, const char *name) iput(inode);
out_free: + up_write(&ubifs_inode(host)->xattr_sem); kfree(xent); return err; }