udf: Allow mounting volumes with incorrect identification strings

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>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 8f2f56d9a1bbfb8b110812d45167ce7e7b456099..e3d684ea320303630f4a75135ed4e4bcc408484c 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -827,16 +827,20 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 
 
        ret = udf_dstrCS0toChar(sb, 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_dstrCS0toChar(sb, 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 45234791fec281f027cc05b97d9364384d8bc7b8..5fcfa96463ebb820cef33b83460fc8d1a9bea8b2 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -351,6 +351,11 @@ static int udf_name_to_CS0(struct super_block *sb,
        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_dstrCS0toChar(struct super_block *sb, uint8_t *utf_o, int o_len,
                      const uint8_t *ocu_i, int i_len)
 {
@@ -359,9 +364,12 @@ int udf_dstrCS0toChar(struct super_block *sb, 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;
                }
        }