This looks like one of the more important of the fixes of this series
- let me know if any thoughts or Reviewed-by/Acked-by on it. I may
try to send this earlier than the others
Pali,
Let me know if I missed dependencies that this patch depends on
On Sat, Oct 5, 2024 at 9:03 AM Pali Rohár <pali@xxxxxxxxxx> wrote:
>
> Check that path buffer has correct length (it is non-zero and in UNICODE
> mode it has even number of bytes) and check that buffer does not contain
> null character (UTF-16 null codepoint in UNICODE mode or null byte in
> non-unicode mode) because Linux cannot process symlink with null byte.
>
> Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> ---
> fs/smb/client/reparse.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
> index 0d1cea64ab6e..fb1d16b17f38 100644
> --- a/fs/smb/client/reparse.c
> +++ b/fs/smb/client/reparse.c
> @@ -544,6 +544,25 @@ int smb2_parse_native_symlink(char **target, const char *buf, unsigned int len,
> int rc;
> int i;
>
> + /* Check that length it valid for unicode/non-unicode mode */
> + if (!len || (unicode && (len % 2))) {
> + cifs_dbg(VFS, "srv returned malformed symlink buffer\n");
> + rc = -EIO;
> + goto out;
> + }
> +
> + /*
> + * Check that buffer does not contain UTF-16 null codepoint in unicode
> + * mode or null byte in non-unicode mode because Linux cannot process
> + * symlink with null byte.
> + */
> + if ((unicode && UniStrnlen((wchar_t *)buf, len/2) != len/2) ||
> + (!unicode && strnlen(buf, len) != len)) {
> + cifs_dbg(VFS, "srv returned null byte in native symlink target location\n");
> + rc = -EIO;
> + goto out;
> + }
> +
> smb_target = cifs_strndup_from_utf16(buf, len, unicode, cifs_sb->local_nls);
> if (!smb_target) {
> rc = -ENOMEM;
> --
> 2.20.1
>
>
--
Thanks,
Steve
