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GNU C Library master sources branch release/2.28/master updated. glibc-2.28-38-g510a25f
- From: carlos at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 12 Nov 2018 12:43:45 -0000
- Subject: GNU C Library master sources branch release/2.28/master updated. glibc-2.28-38-g510a25f
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=510a25f2d208e3b0c86f54b053f61c5b647e4b9b
commit 510a25f2d208e3b0c86f54b053f61c5b647e4b9b
Author: Pochang Chen <johnchen902@gmail.com>
Date: Thu Aug 16 15:24:24 2018 -0400
malloc: Verify size of top chunk.
The House of Force is a well-known technique to exploit heap
overflow. In essence, this exploit takes three steps:
1. Overwrite the size of top chunk with very large value (e.g. -1).
2. Request x bytes from top chunk. As the size of top chunk
is corrupted, x can be arbitrarily large and top chunk will
still be offset by x.
3. The next allocation from top chunk will thus be controllable.
If we verify the size of top chunk at step 2, we can stop such attack.
(cherry picked from commit 30a17d8c95fbfb15c52d1115803b63aaa73a285c)
diff --git a/ChangeLog b/ChangeLog
index 88814e6..44795b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-08-16 Pochang Chen <johnchen902@gmail.com>
+
+ * malloc/malloc.c (_int_malloc.c): Verify size of top chunk.
+
2018-08-13 Joseph Myers <joseph@codesourcery.com>
* sysdeps/unix/sysv/linux/syscall-names.list: Update kernel
diff --git a/malloc/malloc.c b/malloc/malloc.c
index e247c77..9431108 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4076,6 +4076,9 @@ _int_malloc (mstate av, size_t bytes)
victim = av->top;
size = chunksize (victim);
+ if (__glibc_unlikely (size > av->system_mem))
+ malloc_printerr ("malloc(): corrupted top size");
+
if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
{
remainder_size = size - nb;
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 4 ++++
malloc/malloc.c | 3 +++
2 files changed, 7 insertions(+), 0 deletions(-)
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