clean-up-error-handling-in-ext4_fname_setup_filename

   1 ext4 crypto: clean up error handling in ext4_fname_setup_filename
   2
   3 Fix a potential memory leak where fname->crypto_buf.name wouldn't get
   4 freed in some error paths, and also make the error handling easier to
   5 understand/audit.
   6
   7 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   8
   9 ---
  10  fs/ext4/crypto_fname.c | 35 ++++++++++++++++-------------------
  11  1 file changed, 16 insertions(+), 19 deletions(-)
  12
  13 diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c
  14 index 29a2dc9..23af41f 100644
  15 --- a/fs/ext4/crypto_fname.c
  16 +++ b/fs/ext4/crypto_fname.c
  17 @@ -401,7 +401,7 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
  18               ((iname->name[1] == '.') && (iname->len == 2))))) {
  19                 fname->disk_name.name = (unsigned char *) iname->name;
  20                 fname->disk_name.len = iname->len;
  21 -               goto out;
  22 +               return 0;
  23         }
  24         ret = ext4_get_encryption_info(dir);
  25         if (ret)
  26 @@ -411,19 +411,16 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
  27                 ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
  28                                                      &fname->crypto_buf);
  29                 if (ret < 0)
  30 -                       goto out;
  31 +                       return ret;
  32                 ret = ext4_fname_encrypt(dir, iname, &fname->crypto_buf);
  33                 if (ret < 0)
  34 -                       goto out;
  35 +                       goto errout;
  36                 fname->disk_name.name = fname->crypto_buf.name;
  37                 fname->disk_name.len = fname->crypto_buf.len;
  38 -               ret = 0;
  39 -               goto out;
  40 -       }
  41 -       if (!lookup) {
  42 -               ret = -EACCES;
  43 -               goto out;
  44 +               return 0;
  45         }
  46 +       if (!lookup)
  47 +               return -EACCES;
  48
  49         /* We don't have the key and we are doing a lookup; decode the
  50          * user-supplied name
  51 @@ -431,19 +428,17 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
  52         if (iname->name[0] == '_')
  53                 bigname = 1;
  54         if ((bigname && (iname->len != 33)) ||
  55 -           (!bigname && (iname->len > 43))) {
  56 -               ret = -ENOENT;
  57 -       }
  58 +           (!bigname && (iname->len > 43)))
  59 +               return -ENOENT;
  60 +
  61         fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
  62 -       if (fname->crypto_buf.name == NULL) {
  63 -               ret = -ENOMEM;
  64 -               goto out;
  65 -       }
  66 +       if (fname->crypto_buf.name == NULL)
  67 +               return -ENOMEM;
  68         ret = digest_decode(iname->name + bigname, iname->len - bigname,
  69                             fname->crypto_buf.name);
  70         if (ret < 0) {
  71                 ret = -ENOENT;
  72 -               goto out;
  73 +               goto errout;
  74         }
  75         fname->crypto_buf.len = ret;
  76         if (bigname) {
  77 @@ -453,8 +448,10 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
  78                 fname->disk_name.name = fname->crypto_buf.name;
  79                 fname->disk_name.len = fname->crypto_buf.len;
  80         }
  81 -       ret = 0;
  82 -out:
  83 +       return 0;
  84 +errout:
  85 +       kfree(fname->crypto_buf.name);
  86 +       fname->crypto_buf.name = NULL;
  87         return ret;
  88  }
  89