Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 28b8f234 authored by Gao Xiang's avatar Gao Xiang Committed by Greg Kroah-Hartman
Browse files

staging: erofs: fix race of initializing xattrs of a inode at the same time 



commit 62dc45979f3f8cb0ea67302a93bff686f0c46c5a upstream.

In real scenario, there could be several threads accessing xattrs
of the same xattr-uninitialized inode, and init_inode_xattrs()
almost at the same time.

That's actually an unexpected behavior, this patch closes the race.

Fixes: b17500a0 ("staging: erofs: introduce xattr & acl support")
Cc: <stable@vger.kernel.org> # 4.19+
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 53a989a9

drivers/staging/erofs/internal.h

+8 −3
Original line number Diff line number Diff line
@@ -327,12 +327,17 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid) 
	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);

}



#define inode_set_inited_xattr(inode)   (EROFS_V(inode)->flags |= 1)

#define inode_has_inited_xattr(inode)   (EROFS_V(inode)->flags & 1)

/* atomic flag definitions */

#define EROFS_V_EA_INITED_BIT	0



/* bitlock definitions (arranged in reverse order) */

#define EROFS_V_BL_XATTR_BIT	(BITS_PER_LONG - 1)



struct erofs_vnode {

	erofs_nid_t nid;

	unsigned int flags;



	/* atomic flags (including bitlocks) */

	unsigned long flags;



	unsigned char data_mapping_mode;

	/* inline size in bytes */

drivers/staging/erofs/xattr.c

+29 −12
Original line number Diff line number Diff line
@@ -44,17 +44,24 @@ static inline void xattr_iter_end_final(struct xattr_iter *it) 


static int init_inode_xattrs(struct inode *inode)

{

	struct erofs_vnode *const vi = EROFS_V(inode);

	struct xattr_iter it;

	unsigned i;

	struct erofs_xattr_ibody_header *ih;

	struct erofs_sb_info *sbi;

	struct erofs_vnode *vi;

	bool atomic_map;

	int ret = 0;



	if (likely(inode_has_inited_xattr(inode)))

	/* the most case is that xattrs of this inode are initialized. */

	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))

		return 0;



	vi = EROFS_V(inode);

	if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE))

		return -ERESTARTSYS;



	/* someone has initialized xattrs for us? */

	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))

		goto out_unlock;



	/*

	 * bypass all xattr operations if ->xattr_isize is not greater than
@@ -67,13 +74,16 @@ static int init_inode_xattrs(struct inode *inode) 
	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {

		errln("xattr_isize %d of nid %llu is not supported yet",

		      vi->xattr_isize, vi->nid);

		return -ENOTSUPP;

		ret = -ENOTSUPP;

		goto out_unlock;

	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {

		if (unlikely(vi->xattr_isize)) {

			DBG_BUGON(1);

			return -EIO;	/* xattr ondisk layout error */

			ret = -EIO;

			goto out_unlock;	/* xattr ondisk layout error */

		}

		return -ENOATTR;

		ret = -ENOATTR;

		goto out_unlock;

	}



	sbi = EROFS_I_SB(inode);
@@ -81,8 +91,10 @@ static int init_inode_xattrs(struct inode *inode) 
	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);



	it.page = erofs_get_inline_page(inode, it.blkaddr);

	if (IS_ERR(it.page))

		return PTR_ERR(it.page);

	if (IS_ERR(it.page)) {

		ret = PTR_ERR(it.page);

		goto out_unlock;

	}



	/* read in shared xattr array (non-atomic, see kmalloc below) */

	it.kaddr = kmap(it.page);
@@ -95,7 +107,8 @@ static int init_inode_xattrs(struct inode *inode) 
						sizeof(uint), GFP_KERNEL);

	if (!vi->xattr_shared_xattrs) {

		xattr_iter_end(&it, atomic_map);

		return -ENOMEM;

		ret = -ENOMEM;

		goto out_unlock;

	}



	/* let's skip ibody header */
@@ -112,7 +125,8 @@ static int init_inode_xattrs(struct inode *inode) 
			if (IS_ERR(it.page)) {

				kfree(vi->xattr_shared_xattrs);

				vi->xattr_shared_xattrs = NULL;

				return PTR_ERR(it.page);

				ret = PTR_ERR(it.page);

				goto out_unlock;

			}



			it.kaddr = kmap_atomic(it.page);
@@ -125,8 +139,11 @@ static int init_inode_xattrs(struct inode *inode) 
	}

	xattr_iter_end(&it, atomic_map);



	inode_set_inited_xattr(inode);

	return 0;

	set_bit(EROFS_V_EA_INITED_BIT, &vi->flags);



out_unlock:

	clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags);

	return ret;

}



struct xattr_iter_handlers {