* [2.28 COMMITTED] malloc: Mitigate null-byte overflow attacks
@ 2018-01-01 0:00 Carlos O'Donell
0 siblings, 0 replies; only message in thread
From: Carlos O'Donell @ 2018-01-01 0:00 UTC (permalink / raw)
To: GNU C Library (Stable)
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Tested on x86_64. build-many-glibcs run in progress.
--
* malloc/malloc.c (_int_free): Check for corrupt prev_size vs size.
(malloc_consolidate): Likewise.
(cherry picked from commit d6db68e66dff25d12c3bc5641b60cbd7fb6ab44f)
---
ChangeLog | 5 +++++
malloc/malloc.c | 4 ++++
2 files changed, 9 insertions(+)
--
Cheers,
Carlos.
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From 7e40c3f804b5d5dbbc0519565b16101ab22fb899 Mon Sep 17 00:00:00 2001
From: Moritz Eckert <m.eckert@cs.ucsb.edu>
Date: Thu, 16 Aug 2018 21:08:36 -0400
Subject: [PATCH 3/8] malloc: Mitigate null-byte overflow attacks
* malloc/malloc.c (_int_free): Check for corrupt prev_size vs size.
(malloc_consolidate): Likewise.
(cherry picked from commit d6db68e66dff25d12c3bc5641b60cbd7fb6ab44f)
---
ChangeLog | 5 +++++
malloc/malloc.c | 4 ++++
2 files changed, 9 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 44795b2e61..e81991066e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-16 DJ Delorie <dj@delorie.com>
+
+ * malloc/malloc.c (_int_free): Check for corrupt prev_size vs size.
+ (malloc_consolidate): Likewise.
+
2018-08-16 Pochang Chen <johnchen902@gmail.com>
* malloc/malloc.c (_int_malloc.c): Verify size of top chunk.
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 9431108626..7c8bf8413c 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4281,6 +4281,8 @@ _int_free (mstate av, mchunkptr p, int have_lock)
prevsize = prev_size (p);
size += prevsize;
p = chunk_at_offset(p, -((long) prevsize));
+ if (__glibc_unlikely (chunksize(p) != prevsize))
+ malloc_printerr ("corrupted size vs. prev_size while consolidating");
unlink(av, p, bck, fwd);
}
@@ -4442,6 +4444,8 @@ static void malloc_consolidate(mstate av)
prevsize = prev_size (p);
size += prevsize;
p = chunk_at_offset(p, -((long) prevsize));
+ if (__glibc_unlikely (chunksize(p) != prevsize))
+ malloc_printerr ("corrupted size vs. prev_size in fastbins");
unlink(av, p, bck, fwd);
}
--
2.17.2
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