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32 lines
1.1 KiB
32 lines
1.1 KiB
2 years ago
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commit d6db68e66dff25d12c3bc5641b60cbd7fb6ab44f
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Author: Moritz Eckert <m.eckert@cs.ucsb.edu>
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Date: Thu Aug 16 21:08:36 2018 -0400
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malloc: Mitigate null-byte overflow attacks
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* malloc/malloc.c (_int_free): Check for corrupt prev_size vs size.
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(malloc_consolidate): Likewise.
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diff --git a/malloc/malloc.c b/malloc/malloc.c
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index 13c52f376859562d..e450597e2e527fb7 100644
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--- a/malloc/malloc.c
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+++ b/malloc/malloc.c
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@@ -4306,6 +4306,8 @@ _int_free (mstate av, mchunkptr p, int have_lock)
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prevsize = prev_size (p);
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size += prevsize;
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p = chunk_at_offset(p, -((long) prevsize));
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+ if (__glibc_unlikely (chunksize(p) != prevsize))
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+ malloc_printerr ("corrupted size vs. prev_size while consolidating");
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unlink(av, p, bck, fwd);
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}
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@@ -4467,6 +4469,8 @@ static void malloc_consolidate(mstate av)
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prevsize = prev_size (p);
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size += prevsize;
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p = chunk_at_offset(p, -((long) prevsize));
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+ if (__glibc_unlikely (chunksize(p) != prevsize))
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+ malloc_printerr ("corrupted size vs. prev_size in fastbins");
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unlink(av, p, bck, fwd);
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}
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