fix-memory-leaks-in-ext4_encrypted_zeroout

   1 ext4 crypto: fix memory leaks in ext4_encrypted_zeroout
   2
   3 ext4_encrypted_zeroout() could end up leaking a bio and bounce page.
   4 Fortunately it's not used much.  While we're fixing things up,
   5 refactor out common code into the static function alloc_bounce_page()
   6 and fix up error handling if mempool_alloc() fails.
   7
   8 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   9
  10 ---
  11  fs/ext4/crypto.c | 62 +++++++++++++++++++++++++++++++-------------------------------
  12  1 file changed, 31 insertions(+), 31 deletions(-)
  13
  14 diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
  15 index 68c7ab8..ac2419c 100644
  16 --- a/fs/ext4/crypto.c
  17 +++ b/fs/ext4/crypto.c
  18 @@ -324,6 +324,26 @@ static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
  19         return 0;
  20  }
  21
  22 +static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx)
  23 +{
  24 +       struct page *ciphertext_page = alloc_page(GFP_NOFS);
  25 +
  26 +       if (!ciphertext_page) {
  27 +               /* This is a potential bottleneck, but at least we'll have
  28 +                * forward progress. */
  29 +               ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
  30 +                                                GFP_NOFS);
  31 +               if (ciphertext_page == NULL)
  32 +                       return ERR_PTR(-ENOMEM);
  33 +               ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  34 +       } else {
  35 +               ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  36 +       }
  37 +       ctx->flags |= EXT4_WRITE_PATH_FL;
  38 +       ctx->w.bounce_page = ciphertext_page;
  39 +       return ciphertext_page;
  40 +}
  41 +
  42  /**
  43   * ext4_encrypt() - Encrypts a page
  44   * @inode:          The inode for which the encryption should take place
  45 @@ -353,28 +373,17 @@ struct page *ext4_encrypt(struct inode *inode,
  46                 return (struct page *) ctx;
  47
  48         /* The encryption operation will require a bounce page. */
  49 -       ciphertext_page = alloc_page(GFP_NOFS);
  50 -       if (!ciphertext_page) {
  51 -               /* This is a potential bottleneck, but at least we'll have
  52 -                * forward progress. */
  53 -               ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
  54 -                                                GFP_NOFS);
  55 -               if (WARN_ON_ONCE(!ciphertext_page)) {
  56 -                       ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
  57 -                                                        GFP_NOFS | __GFP_WAIT);
  58 -               }
  59 -               ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  60 -       } else {
  61 -               ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  62 -       }
  63 -       ctx->flags |= EXT4_WRITE_PATH_FL;
  64 -       ctx->w.bounce_page = ciphertext_page;
  65 +       ciphertext_page = alloc_bounce_page(ctx);
  66 +       if (IS_ERR(ciphertext_page))
  67 +               goto errout;
  68         ctx->w.control_page = plaintext_page;
  69         err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, plaintext_page->index,
  70                                plaintext_page, ciphertext_page);
  71         if (err) {
  72 +               ciphertext_page = ERR_PTR(err);
  73 +       errout:
  74                 ext4_release_crypto_ctx(ctx);
  75 -               return ERR_PTR(err);
  76 +               return ciphertext_page;
  77         }
  78         SetPagePrivate(ciphertext_page);
  79         set_page_private(ciphertext_page, (unsigned long)ctx);
  80 @@ -434,21 +443,11 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
  81         if (IS_ERR(ctx))
  82                 return PTR_ERR(ctx);
  83
  84 -       ciphertext_page = alloc_page(GFP_NOFS);
  85 -       if (!ciphertext_page) {
  86 -               /* This is a potential bottleneck, but at least we'll have
  87 -                * forward progress. */
  88 -               ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
  89 -                                                GFP_NOFS);
  90 -               if (WARN_ON_ONCE(!ciphertext_page)) {
  91 -                       ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
  92 -                                                        GFP_NOFS | __GFP_WAIT);
  93 -               }
  94 -               ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  95 -       } else {
  96 -               ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
  97 +       ciphertext_page = alloc_bounce_page(ctx);
  98 +       if (IS_ERR(ciphertext_page)) {
  99 +               err = PTR_ERR(ciphertext_page);
 100 +               goto errout;
 101         }
 102 -       ctx->w.bounce_page = ciphertext_page;
 103
 104         while (len--) {
 105                 err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, lblk,
 106 @@ -470,6 +469,7 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 107                         goto errout;
 108                 }
 109                 err = submit_bio_wait(WRITE, bio);
 110 +               bio_put(bio);
 111                 if (err)
 112                         goto errout;
 113         }