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[peerdist] Avoid NULL pointer dereference for plaintext blocks

Avoid accidentally dereferencing a NULL cipher context pointer for
plaintext blocks (which are usually messages with a block length of
zero, indicating a missing block).

Signed-off-by: Michael Brown <mcb30@ipxe.org>
tags/v1.20.1
Michael Brown 9 years ago
parent
commit
0a4805bf94
1 changed files with 10 additions and 7 deletions
  1. 10
    7
      src/net/peerblk.c

+ 10
- 7
src/net/peerblk.c View File

@@ -700,17 +700,20 @@ static int peerblk_parse_header ( struct peerdist_block *peerblk ) {
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 		return -EPROTO;
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 	}
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-	/* Allocate cipher context.  Freeing the cipher context (on
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-	 * error or otherwise) is handled by peerblk_reset().
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+	/* Allocate cipher context, if applicable.  Freeing the cipher
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+	 * context (on error or otherwise) is handled by peerblk_reset().
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 	 */
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 	peerblk->cipher = cipher;
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 	assert ( peerblk->cipherctx == NULL );
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-	peerblk->cipherctx = malloc ( cipher->ctxsize );
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-	if ( ! peerblk->cipherctx )
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-		return -ENOMEM;
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+	if ( cipher ) {
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+		peerblk->cipherctx = malloc ( cipher->ctxsize );
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+		if ( ! peerblk->cipherctx )
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+			return -ENOMEM;
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+	}
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-	/* Initialise cipher */
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-	if ( ( rc = cipher_setkey ( cipher, peerblk->cipherctx, peerblk->secret,
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+	/* Initialise cipher, if applicable */
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+	if ( cipher &&
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+	     ( rc = cipher_setkey ( cipher, peerblk->cipherctx, peerblk->secret,
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 				    keylen ) ) != 0 ) {
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 		DBGC ( peerblk, "PEERBLK %p %d.%d could not set key: %s\n",
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 		       peerblk, peerblk->segment, peerblk->block,

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