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From:   Tong Zhang <ztong0001@gmail.com>
To:     Anders Larsen <al@alarsen.net>, linux-kernel@vger.kernel.org
Cc:     ztong0001@gmail.com
Subject: [PATCH v3] qnx4: qnx4_block_map error handling
Date:   Mon,  2 Nov 2020 18:14:21 -0500
Message-Id: <20201102231420.1833852-1-ztong0001@gmail.com>
In-Reply-To: <e457351a04e04aa084902fd5138d4cae@AcuMS.aculab.com>
References: <e457351a04e04aa084902fd5138d4cae@AcuMS.aculab.com>
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qnx4_block_map() may return -EIO on funny qnx4 fs image, in this case do
not interpret -EIO as a correct block number

Signed-off-by: Tong Zhang <ztong0001@gmail.com>
---
v2: also check other callers according to Anders Larsen's<al@alarsen.net> comment
v3: change error code from EIO to ~0ull to avoid potential compiler
warning on signed/unsigned comparison
 fs/qnx4/dir.c   | 2 ++
 fs/qnx4/inode.c | 6 ++++--
 fs/qnx4/namei.c | 3 +++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
index a6ee23aadd28..0ff7b9f6a887 100644
--- a/fs/qnx4/dir.c
+++ b/fs/qnx4/dir.c
@@ -31,6 +31,8 @@ static int qnx4_readdir(struct file *file, struct dir_context *ctx)
 
 	while (ctx->pos < inode->i_size) {
 		blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
+		if (blknum == ~0ull)
+			return -EIO;
 		bh = sb_bread(inode->i_sb, blknum);
 		if (bh == NULL) {
 			printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
index e8da1cde87b9..b4fff2db6c7e 100644
--- a/fs/qnx4/inode.c
+++ b/fs/qnx4/inode.c
@@ -59,6 +59,8 @@ static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_h
 	QNX4DEBUG((KERN_INFO "qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));
 
 	phys = qnx4_block_map( inode, iblock );
+	if (phys == ~0ull)
+		return -EIO;
 	if ( phys ) {
 		// logical block is before EOF
 		map_bh(bh, inode->i_sb, phys);
@@ -98,12 +100,12 @@ unsigned long qnx4_block_map( struct inode *inode, long iblock )
 				bh = sb_bread(inode->i_sb, i_xblk - 1);
 				if ( !bh ) {
 					QNX4DEBUG((KERN_ERR "qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
-					return -EIO;
+					return ~0ull;
 				}
 				xblk = (struct qnx4_xblk*)bh->b_data;
 				if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
 					QNX4DEBUG((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
-					return -EIO;
+					return ~0ull;
 				}
 			}
 			block = try_extent(&xblk->xblk_xtnts[ix], &offset);
diff --git a/fs/qnx4/namei.c b/fs/qnx4/namei.c
index 8d72221735d7..c665ba730c11 100644
--- a/fs/qnx4/namei.c
+++ b/fs/qnx4/namei.c
@@ -66,6 +66,8 @@ static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
 	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
 		if (!bh) {
 			block = qnx4_block_map(dir, blkofs);
+			if (block == ~0ull)
+				goto out;
 			if (block)
 				bh = sb_bread(dir->i_sb, block);
 			if (!bh) {
@@ -88,6 +90,7 @@ static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
 		blkofs++;
 	}
 	brelse(bh);
+out:
 	*res_dir = NULL;
 	return NULL;
 }
-- 
2.25.1