linux-kernel - [PATCH AUTOSEL 4.19 155/172] NTB: ntb_tool: reading the link file should not end in a NULL byte

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Message-Id: <20200618012218.607130-155-sashal@kernel.org>
Date:   Wed, 17 Jun 2020 21:22:01 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Logan Gunthorpe <logang@...tatee.com>,
        Allen Hubbe <allenbh@...il.com>,
        Alexander Fomichev <fomichev.ru@...il.com>,
        Jon Mason <jdmason@...zu.us>, Sasha Levin <sashal@...nel.org>,
        linux-ntb@...glegroups.com
Subject: [PATCH AUTOSEL 4.19 155/172] NTB: ntb_tool: reading the link file should not end in a NULL byte

From: Logan Gunthorpe <logang@...tatee.com>

[ Upstream commit 912e12813dd03c602e4922fc34709ec4d4380cf0 ]

When running ntb_test this warning is issued:

./ntb_test.sh: line 200: warning: command substitution: ignored null
byte in input

This is caused by the kernel returning one more byte than is necessary
when reading the link file.

Reduce the number of bytes read back to 2 as it was before the
commit that regressed this.

Fixes: 7f46c8b3a552 ("NTB: ntb_tool: Add full multi-port NTB API support")
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Acked-by: Allen Hubbe <allenbh@...il.com>
Tested-by: Alexander Fomichev <fomichev.ru@...il.com>
Signed-off-by: Jon Mason <jdmason@...zu.us>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/ntb/test/ntb_tool.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
index 025747c1568e..311d6ab8d016 100644
--- a/drivers/ntb/test/ntb_tool.c
+++ b/drivers/ntb/test/ntb_tool.c
@@ -504,7 +504,7 @@ static ssize_t tool_peer_link_read(struct file *filep, char __user *ubuf,
 	buf[1] = '\n';
 	buf[2] = '\0';
 
-	return simple_read_from_buffer(ubuf, size, offp, buf, 3);
+	return simple_read_from_buffer(ubuf, size, offp, buf, 2);
 }
 
 static TOOL_FOPS_RDWR(tool_peer_link_fops,
@@ -1690,4 +1690,3 @@ static void __exit tool_exit(void)
 	debugfs_remove_recursive(tool_dbgfs_topdir);
 }
 module_exit(tool_exit);
-
-- 
2.25.1