[PATCH AUTOSEL 4.14 02/26] cifs: don't dereference smb_file_target before null check

[PATCH AUTOSEL 4.14 02/26] cifs: don't dereference smb_file_target before null check

[Sasha Levin]

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 8c6c9bed8773375b1d54ccca2911ec892c59db5d ]

There is a null check on dst_file->private data which suggests
it can be potentially null. However, before this check, pointer
smb_file_target is derived from dst_file->private and dereferenced
in the call to tlink_tcon, hence there is a potential null pointer
deference.

Fix this by assigning smb_file_target and target_tcon after the
null pointer sanity checks.

Detected by CoverityScan, CID#1475302 ("Dereference before null check")

Fixes: 04b38d601239 ("vfs: pull btrfs clone API to vfs layer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifsfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 44a7b2dea688..c5fd5abf7206 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -933,8 +933,8 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
 	struct inode *src_inode = file_inode(src_file);
 	struct inode *target_inode = file_inode(dst_file);
 	struct cifsFileInfo *smb_file_src = src_file->private_data;
-	struct cifsFileInfo *smb_file_target = dst_file->private_data;
-	struct cifs_tcon *target_tcon = tlink_tcon(smb_file_target->tlink);
+	struct cifsFileInfo *smb_file_target;
+	struct cifs_tcon *target_tcon;
 	unsigned int xid;
 	int rc;
 
@@ -948,6 +948,9 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
 		goto out;
 	}
 
+	smb_file_target = dst_file->private_data;
+	target_tcon = tlink_tcon(smb_file_target->tlink);
+
 	/*
 	 * Note: cifs case is easier than btrfs since server responsible for
 	 * checks for proper open modes and file type and if it wants
-- 
2.17.1

[PATCH AUTOSEL 4.14 03/26] cifs: fix return value for cifs_listxattr

[Sasha Levin]

From: Ronnie Sahlberg <lsahlber@redhat.com>

[ 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