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malloc: Check for large bin list corruption when inserting unsorted chunk 

Fixes bug 24216. This patch adds security checks for bk and bk_nextsize pointers
of chunks in large bin when inserting chunk from unsorted bin. It was possible
to write the pointer to victim (newly inserted chunk) to arbitrary memory
locations if bk or bk_nextsize pointers of the next large bin chunk
got corrupted.

(cherry picked from commit 5b06f538c5aee0389ed034f60d90a8884d6d54de)
This commit is contained in:
Adam Maris 2019-03-14 16:51:16 -04:00 committed by Arjun Shankar
parent eaea1dfbe9
commit 52b7cd6e9a
1 changed files with 4 additions and 0 deletions
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4
malloc/malloc.c
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@ -3876,10 +3876,14 @@ _int_malloc (mstate av, size_t bytes)
{
victim->fd_nextsize = fwd;
victim->bk_nextsize = fwd->bk_nextsize;
if (__glibc_unlikely (fwd->bk_nextsize->fd_nextsize != fwd))
malloc_printerr ("malloc(): largebin double linked list corrupted (nextsize)");
fwd->bk_nextsize = victim;
victim->bk_nextsize->fd_nextsize = victim;
}
bck = fwd->bk;
if (bck->fd != fwd)
malloc_printerr ("malloc(): largebin double linked list corrupted (bk)");
}
}
else