From: Osama Abdelkader <osama.abdelkader@gmail.com>
Date: Mon, 1 Dec 2025 12:35:36 +0000 (+0100)
Subject: Fix allocation_index increment in malloc_internal
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=57ce2d8243449bd037d58cbceed2596a3831374a;p=thirdparty%2Fglibc.git

Fix allocation_index increment in malloc_internal

The allocation_index was being incremented before checking if mmap()
succeeds.  If mmap() fails, allocation_index would still be incremented,
creating a gap in the allocations tracking array and making
allocation_index inconsistent with the actual number of successful
allocations.

This fix moves the allocation_index increment to after the mmap()
success check, ensuring it only increments when an allocation actually
succeeds.  This maintains proper tracking for leak detection and
prevents gaps in the allocations array.

Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
---

diff --git a/malloc/tst-interpose-aux.c b/malloc/tst-interpose-aux.c
index cf4b8ab25e..55e9623ae0 100644
--- a/malloc/tst-interpose-aux.c
+++ b/malloc/tst-interpose-aux.c
@@ -157,11 +157,11 @@ malloc_internal (size_t size)
       return NULL;
     }
 
-  size_t index = allocation_index++;
   void *result = mmap (NULL, allocation_size, PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   if (result == MAP_FAILED)
     return NULL;
+  size_t index = allocation_index++;
   allocations[index] = result;
   *allocations[index] = (struct allocation_header)
     {