OTP-8451 Harmless buffer overflow by one byte in asn1 and ram_file_drv.

2 files changed, 22 insertions, 12 deletions

diff --git a/erts/emulator/beam/erl_binary.h b/erts/emulator/beam/erl_binary.h
index 21d4e3fdfd..1f948a9684 100644
--- a/erts/emulator/beam/erl_binary.h
+++ b/erts/emulator/beam/erl_binary.h
@@ -195,10 +195,20 @@ erts_free_aligned_binary_bytes(byte* buf)
     }
 }
 
+/* Explicit extra bytes allocated to counter buggy drivers.
+** These extra bytes where earlier (< R13B04) added by an alignment-bug
+** in this code. Do we dare remove this in some major release (R14?) maybe?
+*/
+#ifdef DEBUG
+#  define CHICKEN_PAD 0
+#else
+#  define CHICKEN_PAD (sizeof(void*) - 1)
+#endif
+
 ERTS_GLB_INLINE Binary *
 erts_bin_drv_alloc_fnf(Uint size)
 {
-    Uint bsize = ERTS_SIZEOF_Binary(size);
+    Uint bsize = ERTS_SIZEOF_Binary(size) + CHICKEN_PAD;
     void *res;
     res = erts_alloc_fnf(ERTS_ALC_T_DRV_BINARY, bsize);
     ERTS_CHK_BIN_ALIGNMENT(res);
@@ -208,7 +218,7 @@ erts_bin_drv_alloc_fnf(Uint size)
 ERTS_GLB_INLINE Binary *
 erts_bin_drv_alloc(Uint size)
 {
-    Uint bsize = ERTS_SIZEOF_Binary(size);
+    Uint bsize = ERTS_SIZEOF_Binary(size) + CHICKEN_PAD;
     void *res;
     res = erts_alloc(ERTS_ALC_T_DRV_BINARY, bsize);
     ERTS_CHK_BIN_ALIGNMENT(res);
@@ -219,7 +229,7 @@ erts_bin_drv_alloc(Uint size)
 ERTS_GLB_INLINE Binary *
 erts_bin_nrml_alloc(Uint size)
 {
-    Uint bsize = ERTS_SIZEOF_Binary(size);
+    Uint bsize = ERTS_SIZEOF_Binary(size) + CHICKEN_PAD;
     void *res;
     res = erts_alloc(ERTS_ALC_T_BINARY, bsize);
     ERTS_CHK_BIN_ALIGNMENT(res);
@@ -230,7 +240,7 @@ ERTS_GLB_INLINE Binary *
 erts_bin_realloc_fnf(Binary *bp, Uint size)
 {
     Binary *nbp;
-    Uint bsize = ERTS_SIZEOF_Binary(size);
+    Uint bsize = ERTS_SIZEOF_Binary(size) + CHICKEN_PAD;
     ASSERT((bp->flags & BIN_FLAG_MAGIC) == 0);
     if (bp->flags & BIN_FLAG_DRV)
 	nbp = erts_realloc_fnf(ERTS_ALC_T_DRV_BINARY, (void *) bp, bsize);
@@ -244,7 +254,7 @@ ERTS_GLB_INLINE Binary *
 erts_bin_realloc(Binary *bp, Uint size)
 {
     Binary *nbp;
-    Uint bsize = ERTS_SIZEOF_Binary(size);
+    Uint bsize = ERTS_SIZEOF_Binary(size) + CHICKEN_PAD;
     ASSERT((bp->flags & BIN_FLAG_MAGIC) == 0);
     if (bp->flags & BIN_FLAG_DRV)
 	nbp = erts_realloc_fnf(ERTS_ALC_T_DRV_BINARY, (void *) bp, bsize);
diff --git a/erts/emulator/drivers/common/ram_file_drv.c b/erts/emulator/drivers/common/ram_file_drv.c
index 2e3aeb981e..4a39a156e6 100644
--- a/erts/emulator/drivers/common/ram_file_drv.c
+++ b/erts/emulator/drivers/common/ram_file_drv.c
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 1997-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 1997-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 /*
@@ -388,7 +388,7 @@ static int ram_file_uuencode(RamFile *f)
 {
     int code_len = UULINE(UNIX_LINE);
     int len = f->end;
-    int usize = (len*4+2)/3 + 2*(len/code_len+1) + 2 + 1;
+    int usize = 4*((len+2)/3) + 2*((len+code_len-1)/code_len) + 2;    
     ErlDrvBinary* bin;
     uchar* inp;
     uchar* outp;
@@ -433,7 +433,7 @@ static int ram_file_uuencode(RamFile *f)
     *outp++ = ' ';   /* this end of file 0 length !!! */
     *outp++ = '\n';
     count += 2;
-
+    ASSERT(count == usize);
     driver_free_binary(f->bin);
     ram_file_set(f, bin, usize, count);
     return numeric_reply(f, count);