Re: [PATCH] Use size_t for mallinfo fields.

["Martin Liška" <mliska@suse.cz>]

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On 7/7/20 3:49 PM, Florian Weimer wrote:
> * Martin Liška:
> 
>> On 7/7/20 2:17 PM, Andreas Schwab wrote:
>>> On Jul 07 2020, Martin Liška wrote:
>>>
>>>> The current int type can easily overflow for allocation of more
>>>> than 4GB.
>>>>
>>>> The following patch changes that to size_t. I guess I need to adjust
>>>> the API version of the function, right?
>>>
>>> Not only that, it breaks the ABI of mallinfo.
>>
>> Sure, so what options do I have? I'm new to glibc so a hint would be
>> appreciated.
> 
> We need to add a new function.  Symbol versioning does not work because
> mallinfo is interposed by alternative mallocs (tcmalloc, Address
> Sanitizer, etc.).  Without the new function name, the interposer does
> not know which ABI the application expects, so it's going to be quite
> messy.
> 
> Thanks,
> Florian
> 

All right, am I closer with the suggested patch?

Martin

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From 514b41592d8f435d066817580e0cec29df15b818 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Tue, 7 Jul 2020 13:58:24 +0200
Subject: [PATCH] Use size_t for mallinfo fields.

The current int type can easily overflow for allocation of more
than 4GB.
---
 malloc/malloc.c    | 27 ++++++++++++++++++++++++++-
 malloc/malloc.h    | 16 +++++++++++++++-
 manual/memory.texi | 22 +++++++++++-----------
 3 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index ee87ddbbf9..9944473a72 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -640,6 +640,8 @@ libc_hidden_proto (__libc_mallopt)
 */
 struct mallinfo __libc_mallinfo(void);
 
+struct mallinfo_compat __libc_mallinfo_compat(void);
+
 
 /*
   pvalloc(size_t n);
@@ -4998,6 +5000,27 @@ __libc_mallinfo (void)
   return m;
 }
 
+struct mallinfo_compat
+__libc_mallinfo_compat (void)
+{
+  struct mallinfo_compat m;
+  struct mallinfo mnew = __libc_mallinfo ();
+
+  m.arena = mnew.arena;
+  m.ordblks = mnew.ordblks;
+  m.smblks = mnew.smblks;
+  m.hblks = mnew.hblks;
+  m.hblkhd = mnew.hblkhd;
+  m.usmblks = mnew.usmblks;
+  m.fsmblks = mnew.fsmblks;
+  m.uordblks = mnew.uordblks;
+  m.fordblks = mnew.fordblks;
+  m.keepcost = mnew.keepcost;
+
+  return m;
+}
+
+
 /*
    ------------------------------ malloc_stats ------------------------------
  */
@@ -5630,8 +5653,10 @@ weak_alias (__libc_memalign, memalign)
 strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
 strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
 strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
-strong_alias (__libc_mallinfo, __mallinfo)
+#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_32)
 weak_alias (__libc_mallinfo, mallinfo)
+compat_symbol (libc, __libc_mallinfo_compat, mallinfo, GLIBC_2_32);
+#endif
 strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
 
 weak_alias (__malloc_stats, malloc_stats)
diff --git a/malloc/malloc.h b/malloc/malloc.h
index a6903fdd54..500012bea8 100644
--- a/malloc/malloc.h
+++ b/malloc/malloc.h
@@ -83,7 +83,7 @@ __THROW __attribute_malloc__;
 
 /* SVID2/XPG mallinfo structure */
 
-struct mallinfo
+struct mallinfo_compat
 {
   int arena;    /* non-mmapped space allocated from system */
   int ordblks;  /* number of free chunks */
@@ -97,6 +97,20 @@ struct mallinfo
   int keepcost; /* top-most, releasable (via malloc_trim) space */
 };
 
+struct mallinfo
+{
+  size_t arena;    /* non-mmapped space allocated from system */
+  size_t ordblks;  /* number of free chunks */
+  size_t smblks;   /* number of fastbin blocks */
+  size_t hblks;    /* number of mmapped regions */
+  size_t hblkhd;   /* space in mmapped regions */
+  size_t usmblks;  /* always 0, preserved for backwards compatibility */
+  size_t fsmblks;  /* space available in freed fastbin blocks */
+  size_t uordblks; /* total allocated space */
+  size_t fordblks; /* total free space */
+  size_t keepcost; /* top-most, releasable (via malloc_trim) space */
+};
+
 /* Returns a copy of the updated current mallinfo. */
 extern struct mallinfo mallinfo (void) __THROW;
 
diff --git a/manual/memory.texi b/manual/memory.texi
index aa5011e4f9..ac803dd2d5 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -1516,39 +1516,39 @@ This structure type is used to return information about the dynamic
 memory allocator.  It contains the following members:
 
 @table @code
-@item int arena
+@item size_t arena
 This is the total size of memory allocated with @code{sbrk} by
 @code{malloc}, in bytes.
 
-@item int ordblks
+@item size_t ordblks
 This is the number of chunks not in use.  (The memory allocator
-internally gets chunks of memory from the operating system, and then
+size_ternally gets chunks of memory from the operating system, and then
 carves them up to satisfy individual @code{malloc} requests;
 @pxref{The GNU Allocator}.)
 
-@item int smblks
+@item size_t smblks
 This field is unused.
 
-@item int hblks
+@item size_t hblks
 This is the total number of chunks allocated with @code{mmap}.
 
-@item int hblkhd
+@item size_t hblkhd
 This is the total size of memory allocated with @code{mmap}, in bytes.
 
-@item int usmblks
+@item size_t usmblks
 This field is unused and always 0.
 
-@item int fsmblks
+@item size_t fsmblks
 This field is unused.
 
-@item int uordblks
+@item size_t uordblks
 This is the total size of memory occupied by chunks handed out by
 @code{malloc}.
 
-@item int fordblks
+@item size_t fordblks
 This is the total size of memory occupied by free (not in use) chunks.
 
-@item int keepcost
+@item size_t keepcost
 This is the size of the top-most releasable chunk that normally
 borders the end of the heap (i.e., the high end of the virtual address
 space's data segment).
-- 
2.27.0