Re: [PATCH v3] Streamer: Fix out of range memory access of machine mode

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

On 2023-06-29T11:29:57+0200, I wrote:
> On 2023-06-21T15:58:24+0800, Pan Li via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>> We extend the machine mode from 8 to 16 bits already. But there still
>> one placing missing from the streamer. It has one hard coded array
>> for the machine code like size 256.
>>
>> In the lto pass, we memset the array by MAX_MACHINE_MODE count but the
>> value of the MAX_MACHINE_MODE will grow as more and more modes are
>> added. While the machine mode array in tree-streamer still leave 256 as is.
>>
>> Then, when the MAX_MACHINE_MODE is greater than 256, the memset of
>> lto_output_init_mode_table will touch the memory out of range unexpected.
>
> Uh.  :-O
>
>> This patch would like to take the MAX_MACHINE_MODE as the size of the
>> array in streamer, to make sure there is no potential unexpected
>> memory access in future. Meanwhile, this patch also adjust some place
>> which has MAX_MACHINE_MODE <= 256 assumption.
>
> Thanks to Jakub and Richard for guidance re the offloading compilation
> case, where we've got different 'MAX_MACHINE_MODE's between stream-out
> and stream-in, and a modes mapping table.
>
> However, with this patch, there are ICEs all over the place...  I'm
> having a look.

Your patch has all the right ideas, there are just a few additional
changes necessary.  Please merge in the attached
"f into Streamer: Fix out of range memory access of machine mode", with
'Co-authored-by: Thomas Schwinge <thomas@codesourcery.com>'.  This has
already survived compiler-side 'lto.exp' testing and
'check-target-libgomp' with Nvidia GPU offloading; AMD GPU testing is now
running (not expecting any bad surprises).  Will let you know by (my)
tomorrow morning in case there are any more problems.

Explanation:

>> --- a/gcc/lto-streamer-in.cc
>> +++ b/gcc/lto-streamer-in.cc
>> @@ -1985,8 +1985,6 @@ lto_input_mode_table (struct lto_file_decl_data *file_data)
>>      internal_error ("cannot read LTO mode table from %s",
>>                   file_data->file_name);
>>
>> -  unsigned char *table = ggc_cleared_vec_alloc<unsigned char> (1 << 8);
>> -  file_data->mode_table = table;
>>    const struct lto_simple_header_with_strings *header
>>      = (const struct lto_simple_header_with_strings *) data;
>>    int string_offset;
>> @@ -1998,16 +1996,22 @@ lto_input_mode_table (struct lto_file_decl_data *file_data)
>>                               header->string_size, vNULL);
>>    bitpack_d bp = streamer_read_bitpack (&ib);
>>
>> +  unsigned mode_bits = bp_unpack_value (&bp, 5);
>> +  unsigned char *table = ggc_cleared_vec_alloc<unsigned char> (1 << mode_bits);
>> +
>> +  file_data->mode_table = table;
>> +  file_data->mode_bits = mode_bits;

Here, we set 'file_data->mode_bits' for the offloading case (where
'lto_input_mode_table' is called) -- but it's not set for the
non-offloading case (where 'lto_input_mode_table' isn't called).  (See my
'gcc/lto/lto-common.cc:lto_read_decls' change.)  That's "not currently a
problem", as 'file_data->mode_bits' isn't used anywhere...

>> --- a/gcc/lto-streamer.h
>> +++ b/gcc/lto-streamer.h
>> @@ -604,6 +604,8 @@ struct GTY(()) lto_file_decl_data
>>    int order_base;
>>
>>    int unit_base;
>> +
>> +  unsigned mode_bits;
>>  };

>>  inline machine_mode
>>  bp_unpack_machine_mode (struct bitpack_d *bp)
>>  {
>> -  return (machine_mode)
>> -        ((class lto_input_block *)
>> -         bp->stream)->mode_table[bp_unpack_enum (bp, machine_mode, 1 << 8)];
>> +  int last = 1 << ceil_log2 (MAX_MACHINE_MODE);
>> +  lto_input_block *input_block = (class lto_input_block *) bp->stream;
>> +  int index = bp_unpack_enum (bp, machine_mode, last);
>> +
>> +  return (machine_mode) input_block->mode_table[index];
>>  }

..., but 'file_data->mode_bits' needs to be considered here, in the
stream-in for offloading, where 'file_data->mode_bits' -- that is, the
host 'MAX_MACHINE_MODE' -- very likely is different from the offload
device 'MAX_MACHINE_MODE'.

Easiest is in 'gcc/lto-streamer.h:class lto_input_block' to capture
'lto_file_decl_data *file_data' instead of just
'unsigned char *mode_table', and adjust all users.

That's it.  :-)

>> --- a/gcc/tree-streamer.h
>> +++ b/gcc/tree-streamer.h

>> @@ -108,15 +108,19 @@ inline void
>>  bp_pack_machine_mode (struct bitpack_d *bp, machine_mode mode)
>>  {
>>    streamer_mode_table[mode] = 1;
>> -  bp_pack_enum (bp, machine_mode, 1 << 8, mode);
>> +  int last = 1 << ceil_log2 (MAX_MACHINE_MODE);
>> +
>> +  bp_pack_enum (bp, machine_mode, last, mode);
>>  }

That use of 'MAX_MACHINE_MODE' is safe, as that only concerns the
stream-out phase.

>> --- a/gcc/tree-streamer.cc
>> +++ b/gcc/tree-streamer.cc
>> @@ -35,7 +35,7 @@ along with GCC; see the file COPYING3.  If not see
>>     During streaming in, we translate the on the disk mode using this
>>     table.  For normal LTO it is set to identity, for ACCEL_COMPILER
>>     depending on the mode_table content.  */
>> -unsigned char streamer_mode_table[1 << 8];
>> +unsigned char streamer_mode_table[MAX_MACHINE_MODE];

Likewise.


Grüße
 Thomas


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From 88ff74f043235735701f71cdb51a83315f8a3895 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Thu, 29 Jun 2023 21:33:06 +0200
Subject: [PATCH] f into Streamer: Fix out of range memory access of machine
 mode

	gcc/
	* lto-streamer.h (class lto_input_block): Capture
	'lto_file_decl_data *file_data' instead of just
	'unsigned char *mode_table'.  Adjust all users.
	* tree-streamer.h (bp_unpack_machine_mode): Use
	'file_data->mode_bits'.
	gcc/lto/
	* lto-common.cc (lto_read_decls) [!ACCEL_COMPILER]: Initialize
	'file_data->mode_bits'.
---
 gcc/ipa-devirt.cc      |  2 +-
 gcc/ipa-fnsummary.cc   |  2 +-
 gcc/ipa-icf.cc         |  2 +-
 gcc/ipa-modref.cc      |  2 +-
 gcc/ipa-prop.cc        |  4 ++--
 gcc/ipa-sra.cc         |  2 +-
 gcc/lto-cgraph.cc      |  2 +-
 gcc/lto-section-in.cc  |  2 +-
 gcc/lto-streamer-in.cc |  6 +++---
 gcc/lto-streamer.h     | 10 +++++-----
 gcc/lto/lto-common.cc  |  3 ++-
 gcc/tree-streamer.h    |  6 +++---
 12 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/gcc/ipa-devirt.cc b/gcc/ipa-devirt.cc
index 2c61a497cee..87529be4515 100644
--- a/gcc/ipa-devirt.cc
+++ b/gcc/ipa-devirt.cc
@@ -4147,7 +4147,7 @@ ipa_odr_read_section (struct lto_file_decl_data *file_data, const char *data,
   class data_in *data_in;
 
   lto_input_block ib ((const char *) data + main_offset, header->main_size,
-		      file_data->mode_table);
+		      file_data);
 
   data_in
     = lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/ipa-fnsummary.cc b/gcc/ipa-fnsummary.cc
index a5f5a50c8a5..37c1edc2f3a 100644
--- a/gcc/ipa-fnsummary.cc
+++ b/gcc/ipa-fnsummary.cc
@@ -4528,7 +4528,7 @@ inline_read_section (struct lto_file_decl_data *file_data, const char *data,
   unsigned int f_count;
 
   lto_input_block ib ((const char *) data + main_offset, header->main_size,
-		      file_data->mode_table);
+		      file_data);
 
   data_in =
     lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/ipa-icf.cc b/gcc/ipa-icf.cc
index cb9f768d85d..836d0914ded 100644
--- a/gcc/ipa-icf.cc
+++ b/gcc/ipa-icf.cc
@@ -2204,7 +2204,7 @@ sem_item_optimizer::read_section (lto_file_decl_data *file_data,
   unsigned int count;
 
   lto_input_block ib_main ((const char *) data + main_offset, 0,
-			   header->main_size, file_data->mode_table);
+			   header->main_size, file_data);
 
   data_in
     = lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/ipa-modref.cc b/gcc/ipa-modref.cc
index e3196df8aa9..278b2dbd828 100644
--- a/gcc/ipa-modref.cc
+++ b/gcc/ipa-modref.cc
@@ -3816,7 +3816,7 @@ read_section (struct lto_file_decl_data *file_data, const char *data,
   unsigned int f_count;
 
   lto_input_block ib ((const char *) data + main_offset, header->main_size,
-		      file_data->mode_table);
+		      file_data);
 
   data_in
     = lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index 704fe01b02c..8f2119b72e3 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -5337,7 +5337,7 @@ ipa_prop_read_section (struct lto_file_decl_data *file_data, const char *data,
   unsigned int count;
 
   lto_input_block ib_main ((const char *) data + main_offset,
-			   header->main_size, file_data->mode_table);
+			   header->main_size, file_data);
 
   data_in =
     lto_data_in_create (file_data, (const char *) data + string_offset,
@@ -5561,7 +5561,7 @@ read_replacements_section (struct lto_file_decl_data *file_data,
   unsigned int count;
 
   lto_input_block ib_main ((const char *) data + main_offset,
-			   header->main_size, file_data->mode_table);
+			   header->main_size, file_data);
 
   data_in = lto_data_in_create (file_data, (const char *) data + string_offset,
 				header->string_size, vNULL);
diff --git a/gcc/ipa-sra.cc b/gcc/ipa-sra.cc
index 21d281a9756..c35e03b7abd 100644
--- a/gcc/ipa-sra.cc
+++ b/gcc/ipa-sra.cc
@@ -2944,7 +2944,7 @@ isra_read_summary_section (struct lto_file_decl_data *file_data,
   unsigned int count;
 
   lto_input_block ib_main ((const char *) data + main_offset,
-			   header->main_size, file_data->mode_table);
+			   header->main_size, file_data);
 
   data_in =
     lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/lto-cgraph.cc b/gcc/lto-cgraph.cc
index aed5e9ddb18..32c0f5ac6db 100644
--- a/gcc/lto-cgraph.cc
+++ b/gcc/lto-cgraph.cc
@@ -2174,7 +2174,7 @@ input_cgraph_opt_section (struct lto_file_decl_data *file_data,
   unsigned int count;
 
   lto_input_block ib_main ((const char *) data + main_offset,
-			   header->main_size, file_data->mode_table);
+			   header->main_size, file_data);
 
   data_in =
     lto_data_in_create (file_data, (const char *) data + string_offset,
diff --git a/gcc/lto-section-in.cc b/gcc/lto-section-in.cc
index 07cf7326582..5ff00a3c130 100644
--- a/gcc/lto-section-in.cc
+++ b/gcc/lto-section-in.cc
@@ -262,7 +262,7 @@ lto_create_simple_input_block (struct lto_file_decl_data *file_data,
 
   *datar = data;
   return new lto_input_block (data + main_offset, header->main_size,
-			      file_data->mode_table);
+			      file_data);
 }
 
 
diff --git a/gcc/lto-streamer-in.cc b/gcc/lto-streamer-in.cc
index 2a0720b4e6f..1876e1967ec 100644
--- a/gcc/lto-streamer-in.cc
+++ b/gcc/lto-streamer-in.cc
@@ -1629,11 +1629,11 @@ lto_read_body_or_constructor (struct lto_file_decl_data *file_data, struct symta
       /* Set up the struct function.  */
       from = data_in->reader_cache->nodes.length ();
       lto_input_block ib_main (data + main_offset, header->main_size,
-			       file_data->mode_table);
+			       file_data);
       if (TREE_CODE (node->decl) == FUNCTION_DECL)
 	{
 	  lto_input_block ib_cfg (data + cfg_offset, header->cfg_size,
-				  file_data->mode_table);
+				  file_data);
 	  input_function (fn_decl, data_in, &ib_main, &ib_cfg,
 			  dyn_cast <cgraph_node *>(node));
 	}
@@ -1954,7 +1954,7 @@ lto_input_toplevel_asms (struct lto_file_decl_data *file_data, int order_base)
   string_offset = sizeof (*header) + header->main_size;
 
   lto_input_block ib (data + sizeof (*header), header->main_size,
-		      file_data->mode_table);
+		      file_data);
 
   data_in = lto_data_in_create (file_data, data + string_offset,
 			      header->string_size, vNULL);
diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
index 443f0cd616e..0556b34c837 100644
--- a/gcc/lto-streamer.h
+++ b/gcc/lto-streamer.h
@@ -344,14 +344,14 @@ public:
   /* Special constructor for the string table, it abuses this to
      do random access but use the uhwi decoder.  */
   lto_input_block (const char *data_, unsigned int p_, unsigned int len_,
-		   const unsigned char *mode_table_)
-      : data (data_), mode_table (mode_table_), p (p_), len (len_) {}
+		   const lto_file_decl_data *file_data_)
+      : data (data_), file_data (file_data_), p (p_), len (len_) {}
   lto_input_block (const char *data_, unsigned int len_,
-		   const unsigned char *mode_table_)
-      : data (data_), mode_table (mode_table_), p (0), len (len_) {}
+		   const lto_file_decl_data *file_data_)
+      : data (data_), file_data (file_data_), p (0), len (len_) {}
 
   const char *data;
-  const unsigned char *mode_table;
+  const lto_file_decl_data *file_data;
   unsigned int p;
   unsigned int len;
 };
diff --git a/gcc/lto/lto-common.cc b/gcc/lto/lto-common.cc
index 537570204b3..973ab791712 100644
--- a/gcc/lto/lto-common.cc
+++ b/gcc/lto/lto-common.cc
@@ -1880,7 +1880,7 @@ lto_read_decls (struct lto_file_decl_data *decl_data, const void *data,
   uint32_t num_decl_states;
 
   lto_input_block ib_main ((const char *) data + main_offset,
-			   header->main_size, decl_data->mode_table);
+			   header->main_size, decl_data);
 
   data_in = lto_data_in_create (decl_data, (const char *) data + string_offset,
 				header->string_size, resolutions);
@@ -2275,6 +2275,7 @@ lto_file_finalize (struct lto_file_decl_data *file_data, lto_file *file,
   lto_input_mode_table (file_data);
 #else
   file_data->mode_table = lto_mode_identity_table;
+  file_data->mode_bits = ceil_log2 (MAX_MACHINE_MODE);
 #endif
 
   data = lto_get_summary_section_data (file_data, LTO_section_decls, &len);
diff --git a/gcc/tree-streamer.h b/gcc/tree-streamer.h
index ff8bccf901a..db01c8c7678 100644
--- a/gcc/tree-streamer.h
+++ b/gcc/tree-streamer.h
@@ -116,11 +116,11 @@ bp_pack_machine_mode (struct bitpack_d *bp, machine_mode mode)
 inline machine_mode
 bp_unpack_machine_mode (struct bitpack_d *bp)
 {
-  int last = 1 << ceil_log2 (MAX_MACHINE_MODE);
-  lto_input_block *input_block = (class lto_input_block *) bp->stream;
+  lto_input_block *ib = (class lto_input_block *) bp->stream;
+  int last = 1 << ib->file_data->mode_bits;
   int index = bp_unpack_enum (bp, machine_mode, last);
 
-  return (machine_mode) input_block->mode_table[index];
+  return (machine_mode) ib->file_data->mode_table[index];
 }
 
 #endif  /* GCC_TREE_STREAMER_H  */
-- 
2.34.1