udf: Allow mounting volumes with incorrect identification strings

BugLink: https://bugs.launchpad.net/bugs/1836968
commit b54e41f5efcb4316b2f30b30c2535cc194270373 upstream.

Commit c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
started to be more strict when checking whether converted strings are
properly formatted. Sudip reports that there are DVDs where the volume
identification string is actually too long - UDF reports:

[  632.309320] UDF-fs: incorrect dstring lengths (32/32)

during mount and fails the mount. This is mostly harmless failure as we
don't need volume identification (and even less volume set
identification) for anything. So just truncate the volume identification
string if it is too long and replace it with 'Invalid' if we just cannot
convert it for other reasons. This keeps slightly incorrect media still
mountable.

CC: stable@vger.kernel.org
Fixes: c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
Reported-and-tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 57ebb1660f1239bee54c60c682d3d7613ae98911..463cb049927a8b6b8b9d194d6932300821e99472 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -919,16 +919,20 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
        }
 
        ret = udf_dstrCS0toUTF8(outstr, 31, pvoldesc->volIdent, 32);
-       if (ret < 0)
-               goto out_bh;
-
-       strncpy(UDF_SB(sb)->s_volume_ident, outstr, ret);
+       if (ret < 0) {
+               strcpy(UDF_SB(sb)->s_volume_ident, "InvalidName");
+               pr_warn("incorrect volume identification, setting to "
+                       "'InvalidName'\n");
+       } else {
+               strncpy(UDF_SB(sb)->s_volume_ident, outstr, ret);
+       }
        udf_debug("volIdent[] = '%s'\n", UDF_SB(sb)->s_volume_ident);
 
        ret = udf_dstrCS0toUTF8(outstr, 127, pvoldesc->volSetIdent, 128);
-       if (ret < 0)
+       if (ret < 0) {
+               ret = 0;
                goto out_bh;
-
+       }
        outstr[ret] = 0;
        udf_debug("volSetIdent[] = '%s'\n", outstr);
 

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 16a8ad21b77eda926b8bef4e004a7f280939af84..43e7ee13b5949037514bc1fa0ed0a428f9082add 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -341,6 +341,11 @@ try_again:
        return u_len;
 }
 
+/*
+ * Convert CS0 dstring to output charset. Warning: This function may truncate
+ * input string if it is too long as it is used for informational strings only
+ * and it is better to truncate the string than to refuse mounting a media.
+ */
 int udf_dstrCS0toUTF8(uint8_t *utf_o, int o_len,
                      const uint8_t *ocu_i, int i_len)
 {
@@ -349,9 +354,12 @@ int udf_dstrCS0toUTF8(uint8_t *utf_o, int o_len,
        if (i_len > 0) {
                s_len = ocu_i[i_len - 1];
                if (s_len >= i_len) {
-                       pr_err("incorrect dstring lengths (%d/%d)\n",
-                              s_len, i_len);
-                       return -EINVAL;
+                       pr_warn("incorrect dstring lengths (%d/%d),"
+                               " truncating\n", s_len, i_len);
+                       s_len = i_len - 1;
+                       /* 2-byte encoding? Need to round properly... */
+                       if (ocu_i[0] == 16)
+                               s_len -= (s_len - 1) & 2;
                }
        }