[PATCH v2 08/51] powerpc/pseries/lparcfg: don't drop the last byte of a write

[Christian Brauner <brauner@kernel.org>]

lparcfg_write() terminates its copy of the write by overwriting the
last byte, so a write without a trailing newline loses its last
character: "partition_entitled_capacity=5" is parsed as an empty value
and fails with -EINVAL. Terminate behind the copy instead, and refuse a
write that fills the whole buffer, which can't be terminated.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 arch/powerpc/platforms/pseries/lparcfg.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index 3280b7968cab..9882f98c0efb 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -699,13 +699,12 @@ static ssize_t lparcfg_write(struct file *file, const char __user * buf,
 	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
 		return -EINVAL;
 
-	if (count == 0 || count > sizeof(kbuf))
+	if (count == 0 || count >= sizeof(kbuf))
 		return -EINVAL;
 
 	if (copy_from_user(kbuf, buf, count))
 		return -EFAULT;
-
-	kbuf[count - 1] = '\0';
+	kbuf[count] = '\0';
 	tmp = strchr(kbuf, '=');
 	if (!tmp)
 		return -EINVAL;

-- 
2.53.0