malloc: Add missing locks for some paths (valloc/memalign/posix_memalign)
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Message ID 1569325132-22320-1-git-send-email-oftedal@gmail.com
State New
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Series
  • malloc: Add missing locks for some paths (valloc/memalign/posix_memalign)
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Commit Message

Kjetil Oftedal Sept. 24, 2019, 11:38 a.m. UTC
The internal heap structures were not protected properly in
memalign(). If multiple threads were concurrently allocating memory and
one of them were requesting aligned memory via valloc,memalign or
posix_memalign the internal heap data structures could be corrupted.

Signed-off-by: Kjetil Oftedal <oftedal@gmail.com>
---
 libc/stdlib/malloc/memalign.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Patch
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diff --git a/libc/stdlib/malloc/memalign.c b/libc/stdlib/malloc/memalign.c
index 74d5dbd..0d3de67 100644
--- a/libc/stdlib/malloc/memalign.c
+++ b/libc/stdlib/malloc/memalign.c
@@ -77,7 +77,9 @@  memalign (size_t alignment, size_t size)
 	  init_size = addr - tot_addr;
 	}
 
+      __heap_lock (&__malloc_heap_lock);
       __heap_free (heap, base, init_size);
+      __heap_unlock (&__malloc_heap_lock);
 
       /* Remember that we've freed the initial part of MEM.  */
       base += init_size;
@@ -85,9 +87,11 @@  memalign (size_t alignment, size_t size)
 
   /* Return the end part of MEM to the heap, unless it's too small.  */
   end_addr = addr + size;
-  if (end_addr + MALLOC_REALLOC_MIN_FREE_SIZE < tot_end_addr)
+  if (end_addr + MALLOC_REALLOC_MIN_FREE_SIZE < tot_end_addr) {
+    __heap_lock (&__malloc_heap_lock);
     __heap_free (heap, (void *)end_addr, tot_end_addr - end_addr);
-  else
+    __heap_unlock (&__malloc_heap_lock);
+  } else
     /* We didn't free the end, so include it in the size.  */
     end_addr = tot_end_addr;