cifs: fix return value for cifs_listxattr

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>
This commit is contained in:
Ronnie Sahlberg 2018-10-25 15:43:36 +10:00 committed by Steve French
parent 5f21585384
commit 0c5d6cb664

View file

@ -747,6 +747,7 @@ 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) {
@ -782,9 +783,10 @@ 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;
@ -792,8 +794,7 @@ 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;