* [PATCH] MTE: Do not pad size in realloc_check
@ 2020-12-22 15:59 Siddhesh Poyarekar
2020-12-22 17:02 ` H.J. Lu
0 siblings, 1 reply; 4+ messages in thread
From: Siddhesh Poyarekar @ 2020-12-22 15:59 UTC (permalink / raw)
To: libc-alpha; +Cc: schwab, rearnsha
The MTE patch to add malloc support incorrectly padded the size passed
to _int_realloc by SIZE_SZ when it ought to have sent just the
chunksize. Revert that bit of the change so that realloc works
correctly with MALLOC_CHECK_ set.
This also brings the realloc_check implementation back in sync with
libc_realloc.
---
malloc/hooks.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/malloc/hooks.c b/malloc/hooks.c
index 8a1c16dfa4..6474ba8b38 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -315,7 +315,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
__libc_lock_unlock (main_arena.mutex);
if (!oldp)
malloc_printerr ("realloc(): invalid pointer");
- const INTERNAL_SIZE_T oldchsize = CHUNK_AVAILABLE_SIZE (oldp);
+ const INTERNAL_SIZE_T oldsize = chunksize (oldp);
if (!checked_request2size (rb, &chnb))
goto invert;
@@ -331,7 +331,8 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
else
#endif
{
- if (oldchsize >= chnb)
+ /* Note the extra SIZE_SZ overhead. */
+ if (oldsize - SIZE_SZ >= chnb)
newmem = oldmem; /* do nothing */
else
{
@@ -340,7 +341,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
newmem = _int_malloc (&main_arena, rb);
if (newmem)
{
- memcpy (newmem, oldmem, oldchsize - CHUNK_HDR_SZ);
+ memcpy (newmem, oldmem, oldsize - CHUNK_HDR_SZ);
munmap_chunk (oldp);
}
}
@@ -349,7 +350,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
else
{
top_check ();
- newmem = _int_realloc (&main_arena, oldp, oldchsize, chnb);
+ newmem = _int_realloc (&main_arena, oldp, oldsize, chnb);
}
DIAG_PUSH_NEEDS_COMMENT;
--
2.29.2
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] MTE: Do not pad size in realloc_check
2020-12-22 15:59 [PATCH] MTE: Do not pad size in realloc_check Siddhesh Poyarekar
@ 2020-12-22 17:02 ` H.J. Lu
2020-12-23 7:46 ` Siddhesh Poyarekar
0 siblings, 1 reply; 4+ messages in thread
From: H.J. Lu @ 2020-12-22 17:02 UTC (permalink / raw)
To: Siddhesh Poyarekar; +Cc: GNU C Library, Andreas Schwab, Richard Earnshaw
On Tue, Dec 22, 2020 at 8:00 AM Siddhesh Poyarekar via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> The MTE patch to add malloc support incorrectly padded the size passed
> to _int_realloc by SIZE_SZ when it ought to have sent just the
> chunksize. Revert that bit of the change so that realloc works
> correctly with MALLOC_CHECK_ set.
>
> This also brings the realloc_check implementation back in sync with
> libc_realloc.
> ---
> malloc/hooks.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/malloc/hooks.c b/malloc/hooks.c
> index 8a1c16dfa4..6474ba8b38 100644
> --- a/malloc/hooks.c
> +++ b/malloc/hooks.c
> @@ -315,7 +315,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
> __libc_lock_unlock (main_arena.mutex);
> if (!oldp)
> malloc_printerr ("realloc(): invalid pointer");
> - const INTERNAL_SIZE_T oldchsize = CHUNK_AVAILABLE_SIZE (oldp);
> + const INTERNAL_SIZE_T oldsize = chunksize (oldp);
>
> if (!checked_request2size (rb, &chnb))
> goto invert;
> @@ -331,7 +331,8 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
> else
> #endif
> {
> - if (oldchsize >= chnb)
> + /* Note the extra SIZE_SZ overhead. */
> + if (oldsize - SIZE_SZ >= chnb)
> newmem = oldmem; /* do nothing */
> else
> {
> @@ -340,7 +341,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
> newmem = _int_malloc (&main_arena, rb);
> if (newmem)
> {
> - memcpy (newmem, oldmem, oldchsize - CHUNK_HDR_SZ);
> + memcpy (newmem, oldmem, oldsize - CHUNK_HDR_SZ);
> munmap_chunk (oldp);
> }
> }
> @@ -349,7 +350,7 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
> else
> {
> top_check ();
> - newmem = _int_realloc (&main_arena, oldp, oldchsize, chnb);
> + newmem = _int_realloc (&main_arena, oldp, oldsize, chnb);
> }
>
> DIAG_PUSH_NEEDS_COMMENT;
Please add some tests with MALLOC_CHECK_=.
--
H.J.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-12-23 13:52 UTC | newest]
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2020-12-22 15:59 [PATCH] MTE: Do not pad size in realloc_check Siddhesh Poyarekar
2020-12-22 17:02 ` H.J. Lu
2020-12-23 7:46 ` Siddhesh Poyarekar
2020-12-23 13:51 ` H.J. Lu
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