malloc_stats(): Fix `unsigned int` overflow
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Commit Message
Fixes malloc_stats() returning vastly wrong information for programs
that use more than 2 GiB memory.
`man mallinfo` documents that it uses `int` and wraps around, but
`man malloc_stats` does not, and should not.
Fixes https://sourceware.org/bugzilla/show_bug.cgi?id=21556
Signed-off-by: Niklas Hambüchen <mail@nh2.me>
---
malloc/malloc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
Comments
Fails 32-bit build:
https://www.delorie.com/trybots/32bit/4291/make.tail.txt
The error:
> malloc.c:5169:48: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
glibc doesn't require C99, so I guess "%zu" is not an option, right?
Since this is just in an `fprintf`, would casting to `(unsigned long long)` and using "%llu" be considered acceptable?
Niklas
On 10/30/21 06:06, Niklas Hambüchen via Libc-alpha wrote:
> The error:
>
>> malloc.c:5169:48: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
>
> glibc doesn't require C99, so I guess "%zu" is not an option, right?
%zu is already being used in the file you're changing, so it's perfectly
fine to use.
Siddhesh
On Okt 30 2021, Niklas Hambüchen via Libc-alpha wrote:
> glibc doesn't require C99, so I guess "%zu" is not an option, right?
glibc _implements_ C99, so you can use all its features.
Andreas.
On 29/10/2021 21:36, Niklas Hambüchen via Libc-alpha wrote:
> The error:
>
>> malloc.c:5169:48: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
>
> glibc doesn't require C99, so I guess "%zu" is not an option, right?
We build glibc with -std=gnu11, so we do require a compile that at least support
C11.
>
> Since this is just in an `fprintf`, would casting to `(unsigned long long)` and using "%llu" be considered acceptable?
Either way would be fine.
@@ -5151,7 +5151,7 @@ __malloc_stats (void)
{
int i;
mstate ar_ptr;
- unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
+ size_t in_use_b = mp_.mmapped_mem, system_b = in_use_b;
if (!__malloc_initialized)
ptmalloc_init ();
@@ -5166,8 +5166,8 @@ __malloc_stats (void)
__libc_lock_lock (ar_ptr->mutex);
int_mallinfo (ar_ptr, &mi);
fprintf (stderr, "Arena %d:\n", i);
- fprintf (stderr, "system bytes = %10u\n", (unsigned int) mi.arena);
- fprintf (stderr, "in use bytes = %10u\n", (unsigned int) mi.uordblks);
+ fprintf (stderr, "system bytes = %10lu\n", mi.arena);
+ fprintf (stderr, "in use bytes = %10lu\n", mi.uordblks);
#if MALLOC_DEBUG > 1
if (i > 0)
dump_heap (heap_for_ptr (top (ar_ptr)));
@@ -5180,9 +5180,9 @@ __malloc_stats (void)
break;
}
fprintf (stderr, "Total (incl. mmap):\n");
- fprintf (stderr, "system bytes = %10u\n", system_b);
- fprintf (stderr, "in use bytes = %10u\n", in_use_b);
- fprintf (stderr, "max mmap regions = %10u\n", (unsigned int) mp_.max_n_mmaps);
+ fprintf (stderr, "system bytes = %10lu\n", system_b);
+ fprintf (stderr, "in use bytes = %10lu\n", in_use_b);
+ fprintf (stderr, "max mmap regions = %10d\n", mp_.max_n_mmaps);
fprintf (stderr, "max mmap bytes = %10lu\n",
(unsigned long) mp_.max_mmapped_mem);
stderr->_flags2 = old_flags2;