On 9/12/22 18:08, Dan Carpenter wrote:
Smatch complains that the "add_bytes" is not to be trusted. Use
size_add() to prevent an integer overflow.
Fixes: be71b5cba2e6 ("fs/ntfs3: Add attrib operations")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
The add_bytes variable comes from:
add = ALIGN(struct_size(ea_all, name, 1 + name_len + val_size), 4);
This is problematic and has inspired a new static checker warning:
fs/ntfs3/xattr.c:26 unpacked_ea_size() warn: using integer overflow function 'size_add()' for math
fs/ntfs3/xattr.c:290 ntfs_set_ea() warn: using integer overflow function 'size_add()' for math
The issue is that the struct_size() has an integer overflow and we call
ALIGN() on it, then "add" becomes zero. Is there a bounds check that
we could use here?
add = struct_size(ea_all, name, 1 + name_len + val_size);
if (add > SOMETHING_MAX)
return -EINVAL;
Otherwise the limit would have to be if (add > ULONG_MAX - 3) { which
is ugly.
fs/ntfs3/xattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index 7de8718c68a9..ea582b4fe1d9 100644
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -107,7 +107,7 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
return -EFBIG;
/* Allocate memory for packed Ea. */
- ea_p = kmalloc(size + add_bytes, GFP_NOFS);
+ ea_p = kmalloc(size_add(size, add_bytes), GFP_NOFS);
if (!ea_p)
return -ENOMEM;
Applied, thanks!
