[PATCH 4.19 1/5] staging: erofs: add error handling for xattr submodule

[Gao Xiang]

commit cadf1ccf1b0021d0b7a9347e102ac5258f9f98c8 upstream.

This patch enhances the missing error handling code for
xattr submodule, which improves the stability for the rare cases.

Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
---

This series resolves the following conflicts:
 FAILED: patch "[PATCH] staging: erofs: fix fast symlink w/o xattr when fs xattr is" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: fix memleak of inode's shared xattr array" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: fix race of initializing xattrs of a inode at" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: keep corrupted fs from crashing kernel in" failed to apply to 4.19-stable tree

In addition, there is another patch called
 staging: erofs: add error handling for xattr submodule
that needs to be backported to 4.19 as well (4.20+ already has this patch.)

 drivers/staging/erofs/internal.h |   5 +-
 drivers/staging/erofs/xattr.c    | 112 +++++++++++++++++++++++++++------------
 2 files changed, 81 insertions(+), 36 deletions(-)

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 9f44ed8f0023..1c048c412fb2 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -485,8 +485,9 @@ struct erofs_map_blocks_iter {
 };
 
 
-static inline struct page *erofs_get_inline_page(struct inode *inode,
-	erofs_blk_t blkaddr)
+static inline struct page *
+erofs_get_inline_page(struct inode *inode,
+		      erofs_blk_t blkaddr)
 {
 	return erofs_get_meta_page(inode->i_sb,
 		blkaddr, S_ISDIR(inode->i_mode));
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 0e9cfeccdf99..d4bccb57e7c3 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -24,16 +24,25 @@ struct xattr_iter {
 
 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
 {
-	/* only init_inode_xattrs use non-atomic once */
+	/* the only user of kunmap() is 'init_inode_xattrs' */
 	if (unlikely(!atomic))
 		kunmap(it->page);
 	else
 		kunmap_atomic(it->kaddr);
+
 	unlock_page(it->page);
 	put_page(it->page);
 }
 
-static void init_inode_xattrs(struct inode *inode)
+static inline void xattr_iter_end_final(struct xattr_iter *it)
+{
+	if (!it->page)
+		return;
+
+	xattr_iter_end(it, true);
+}
+
+static int init_inode_xattrs(struct inode *inode)
 {
 	struct xattr_iter it;
 	unsigned i;
@@ -43,7 +52,7 @@ static void init_inode_xattrs(struct inode *inode)
 	bool atomic_map;
 
 	if (likely(inode_has_inited_xattr(inode)))
-		return;
+		return 0;
 
 	vi = EROFS_V(inode);
 	BUG_ON(!vi->xattr_isize);
@@ -53,7 +62,8 @@ static void 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);
-	BUG_ON(IS_ERR(it.page));
+	if (IS_ERR(it.page))
+		return PTR_ERR(it.page);
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -62,9 +72,12 @@ static void init_inode_xattrs(struct inode *inode)
 	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
 
 	vi->xattr_shared_count = ih->h_shared_count;
-	vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
-		vi->xattr_shared_count, sizeof(unsigned),
-		GFP_KERNEL | __GFP_NOFAIL);
+	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
+						sizeof(uint), GFP_KERNEL);
+	if (!vi->xattr_shared_xattrs) {
+		xattr_iter_end(&it, atomic_map);
+		return -ENOMEM;
+	}
 
 	/* let's skip ibody header */
 	it.ofs += sizeof(struct erofs_xattr_ibody_header);
@@ -77,7 +90,8 @@ static void init_inode_xattrs(struct inode *inode)
 
 			it.page = erofs_get_meta_page(inode->i_sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			BUG_ON(IS_ERR(it.page));
+			if (IS_ERR(it.page))
+				return PTR_ERR(it.page);
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;
@@ -90,6 +104,7 @@ static void init_inode_xattrs(struct inode *inode)
 	xattr_iter_end(&it, atomic_map);
 
 	inode_set_inited_xattr(inode);
+	return 0;
 }
 
 struct xattr_iter_handlers {
@@ -99,18 +114,25 @@ struct xattr_iter_handlers {
 	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
 };
 
-static void xattr_iter_fixup(struct xattr_iter *it)
+static inline int xattr_iter_fixup(struct xattr_iter *it)
 {
-	if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
-		xattr_iter_end(it, true);
+	if (it->ofs < EROFS_BLKSIZ)
+		return 0;
 
-		it->blkaddr += erofs_blknr(it->ofs);
-		it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
-		BUG_ON(IS_ERR(it->page));
+	xattr_iter_end(it, true);
 
-		it->kaddr = kmap_atomic(it->page);
-		it->ofs = erofs_blkoff(it->ofs);
+	it->blkaddr += erofs_blknr(it->ofs);
+	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+	if (IS_ERR(it->page)) {
+		int err = PTR_ERR(it->page);
+
+		it->page = NULL;
+		return err;
 	}
+
+	it->kaddr = kmap_atomic(it->page);
+	it->ofs = erofs_blkoff(it->ofs);
+	return 0;
 }
 
 static int inline_xattr_iter_begin(struct xattr_iter *it,
@@ -132,21 +154,24 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 	it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
 
 	it->page = erofs_get_inline_page(inode, it->blkaddr);
-	BUG_ON(IS_ERR(it->page));
-	it->kaddr = kmap_atomic(it->page);
+	if (IS_ERR(it->page))
+		return PTR_ERR(it->page);
 
+	it->kaddr = kmap_atomic(it->page);
 	return vi->xattr_isize - xattr_header_sz;
 }
 
 static int xattr_foreach(struct xattr_iter *it,
-	struct xattr_iter_handlers *op, unsigned *tlimit)
+	const struct xattr_iter_handlers *op, unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
 	unsigned value_sz, processed, slice;
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
-	xattr_iter_fixup(it);
+	err = xattr_iter_fixup(it);
+	if (err)
+		return err;
 
 	/*
 	 * 1. read xattr entry to the memory,
@@ -178,7 +203,9 @@ static int xattr_foreach(struct xattr_iter *it,
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
 
-			xattr_iter_fixup(it);
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -210,7 +237,10 @@ static int xattr_foreach(struct xattr_iter *it,
 	while (processed < value_sz) {
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
-			xattr_iter_fixup(it);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -270,7 +300,7 @@ static void xattr_copyvalue(struct xattr_iter *_it,
 	memcpy(it->buffer + processed, buf, len);
 }
 
-static struct xattr_iter_handlers find_xattr_handlers = {
+static const struct xattr_iter_handlers find_xattr_handlers = {
 	.entry = xattr_entrymatch,
 	.name = xattr_namematch,
 	.alloc_buffer = xattr_checkbuffer,
@@ -291,8 +321,11 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -315,8 +348,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -324,9 +359,12 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -351,7 +389,9 @@ int erofs_getxattr(struct inode *inode, int index,
 	if (unlikely(name == NULL))
 		return -EINVAL;
 
-	init_inode_xattrs(inode);
+	ret = init_inode_xattrs(inode);
+	if (ret)
+		return ret;
 
 	it.index = index;
 
@@ -494,7 +534,7 @@ static int xattr_skipvalue(struct xattr_iter *_it,
 	return 1;
 }
 
-static struct xattr_iter_handlers list_xattr_handlers = {
+static const struct xattr_iter_handlers list_xattr_handlers = {
 	.entry = xattr_entrylist,
 	.name = xattr_namelist,
 	.alloc_buffer = xattr_skipvalue,
@@ -516,7 +556,7 @@ static int inline_listxattr(struct listxattr_iter *it)
 		if (ret < 0)
 			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 	return ret < 0 ? ret : it->buffer_ofs;
 }
 
@@ -538,8 +578,10 @@ static int shared_listxattr(struct listxattr_iter *it)
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -549,7 +591,7 @@ static int shared_listxattr(struct listxattr_iter *it)
 			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_ofs;
 }
@@ -560,7 +602,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	int ret;
 	struct listxattr_iter it;
 
-	init_inode_xattrs(d_inode(dentry));
+	ret = init_inode_xattrs(d_inode(dentry));
+	if (ret)
+		return ret;
 
 	it.dentry = dentry;
 	it.buffer = buffer;
-- 
2.14.5