[PATCH 4.14 02/62] cifs: fix return value for cifs_listxattr

Greg Kroah-Hartman
2018-11-26T10:59:25Z

[ Upstream commit 0c5d6cb6643f48ad3775322f3ebab6c7eb67484e ]

If the application buffer was too small to fit all the names
we would still count the number of bytes and return this for
listxattr. This would then trigger a BUG in usercopy.c

Fix the computation of the size so that we return -ERANGE
correctly when the buffer is too small.

This fixes the kernel BUG for xfstest generic/377

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/smb2ops.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 4e5b05263e4a..3372eedaa94d 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -441,6 +441,7 @@ move_smb2_ea_to_cifs(char *dst, size_t dst_size,
int rc = 0;
unsigned int ea_name_len = ea_name ? strlen(ea_name) : 0;
char *name, *value;
+ size_t buf_size = dst_size;
size_t name_len, value_len, user_name_len;

while (src_size > 0) {
@@ -476,9 +477,10 @@ move_smb2_ea_to_cifs(char *dst, size_t dst_size,
/* 'user.' plus a terminating null */
user_name_len = 5 + 1 + name_len;

- rc += user_name_len;
-
- if (dst_size >= user_name_len) {
+ if (buf_size == 0) {
+ /* skip copy - calc size only */
+ rc += user_name_len;
+ } else if (dst_size >= user_name_len) {
dst_size -= user_name_len;
memcpy(dst, "user.", 5);
dst += 5;
@@ -486,8 +488,7 @@ move_smb2_ea_to_cifs(char *dst, size_t dst_size,
dst += name_len;
*dst = 0;
++dst;
- } else if (dst_size == 0) {
- /* skip copy - calc size only */
+ rc += user_name_len;
} else {
/* stop before overrun buffer */
rc = -ERANGE;
--
2.17.1