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* [glibc] malloc: Switch global_max_fast to uint8_t
@ 2022-10-13  4:18 Florian Weimer
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From: Florian Weimer @ 2022-10-13  4:18 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=15a94e6668a6d7c5697e805d8d67f1d102d0d52e

commit 15a94e6668a6d7c5697e805d8d67f1d102d0d52e
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Oct 13 05:45:41 2022 +0200

    malloc: Switch global_max_fast to uint8_t
    
    MAX_FAST_SIZE is 160 at most, so a uint8_t is sufficient.  This makes
    it harder to use memory corruption, by overwriting global_max_fast
    with a large value, to fundamentally alter malloc behavior.
    
    Reviewed-by: DJ Delorie <dj@redhat.com>

Diff:
---
 malloc/malloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 953183e956..2a61c8b5ee 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1757,7 +1757,7 @@ typedef struct malloc_chunk *mfastbinptr;
 #define set_contiguous(M)      ((M)->flags &= ~NONCONTIGUOUS_BIT)
 
 /* Maximum size of memory handled in fastbins.  */
-static INTERNAL_SIZE_T global_max_fast;
+static uint8_t global_max_fast;
 
 /*
    Set value of max_fast.

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