executor: added syz_io_uring_setup to wrap both setup and mmap

It is hard for the fuzzer to generate correct programs using mmap calls
with fuzzer-provided mmap length. This wrapper ensures correct length
computation.

1 files changed, 85 insertions, 1 deletions

diff --git a/executor/common_linux.h b/executor/common_linux.h
index 546e60b79..a7dfa2374 100644
--- a/executor/common_linux.h
+++ b/executor/common_linux.h
@@ -1355,7 +1355,7 @@ static long syz_emit_ethernet(volatile long a0, volatile long a1, volatile long
 }
 #endif
 
-#if SYZ_EXECUTOR || __NR_syz_io_uring_submit || __NR_syz_io_uring_complete
+#if SYZ_EXECUTOR || __NR_syz_io_uring_submit || __NR_syz_io_uring_complete || __NR_syz_io_uring_setup
 
 #define SIZEOF_IO_URING_SQE 64
 #define SIZEOF_IO_URING_CQE 16
@@ -1435,6 +1435,90 @@ static long syz_io_uring_complete(volatile long a0)
 
 #endif
 
+#if SYZ_EXECUTOR || __NR_syz_io_uring_setup
+
+struct io_sqring_offsets {
+	uint32 head;
+	uint32 tail;
+	uint32 ring_mask;
+	uint32 ring_entries;
+	uint32 flags;
+	uint32 dropped;
+	uint32 array;
+	uint32 resv1;
+	uint64 resv2;
+};
+
+struct io_cqring_offsets {
+	uint32 head;
+	uint32 tail;
+	uint32 ring_mask;
+	uint32 ring_entries;
+	uint32 overflow;
+	uint32 cqes;
+	uint64 resv[2];
+};
+
+struct io_uring_params {
+	uint32 sq_entries;
+	uint32 cq_entries;
+	uint32 flags;
+	uint32 sq_thread_cpu;
+	uint32 sq_thread_idle;
+	uint32 features;
+	uint32 resv[4];
+	struct io_sqring_offsets sq_off;
+	struct io_cqring_offsets cq_off;
+};
+
+#define IORING_OFF_SQ_RING 0
+#define IORING_OFF_SQES 0x10000000ULL
+
+#include <sys/mman.h>
+#include <unistd.h>
+
+#ifndef __NR_io_uring_setup
+#ifdef __alpha__
+#define __NR_io_uring_setup 535
+#else // !__alpha__
+#define __NR_io_uring_setup 425
+#endif
+#endif // __NR_io_uring_setup
+
+// Wrapper for io_uring_setup and the subsequent mmap calls that map the ring and the sqes
+static long syz_io_uring_setup(volatile long a0, volatile long a1, volatile long a2, volatile long a3, volatile long a4, volatile long a5)
+{
+	// syzlang: syz_io_uring_setup(entries int32[1:IORING_MAX_ENTRIES], params ptr[inout, io_uring_params], addr_ring vma, addr_sqes vma, ring_ptr ptr[out, ring_ptr], sqes_ptr ptr[out, sqes_ptr]) fd_io_uring
+	// C:       syz_io_uring_setup(uint32 entries, struct io_uring_params* params, void* mmap_addr_ring, void* mmap_addr_sqes, void** ring_ptr_out, void** sqes_ptr_out) // returns uint32 fd_io_uring
+
+	// Cast to original
+	uint32 entries = (uint32)a0;
+	struct io_uring_params* setup_params = (struct io_uring_params*)a1;
+	void* vma1 = (void*)a2;
+	void* vma2 = (void*)a3;
+	void** ring_ptr_out = (void**)a4;
+	void** sqes_ptr_out = (void**)a5;
+
+	uint32 fd_io_uring = syscall(__NR_io_uring_setup, entries, setup_params);
+
+	// Compute the ring sizes
+	uint32 sq_ring_sz = setup_params->sq_off.array + setup_params->sq_entries * sizeof(uint32);
+	uint32 cq_ring_sz = setup_params->cq_off.cqes + setup_params->cq_entries * SIZEOF_IO_URING_CQE;
+
+	// Asssumed IORING_FEAT_SINGLE_MMAP, which is always the case with the current implementation
+	// The implication is that the sq_ring_ptr and the cq_ring_ptr are the same but the
+	// difference is in the offsets to access the fields of these rings.
+	uint32 ring_sz = sq_ring_sz > cq_ring_sz ? sq_ring_sz : cq_ring_sz;
+	*ring_ptr_out = mmap(vma1, ring_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQ_RING);
+
+	uint32 sqes_sz = setup_params->sq_entries * SIZEOF_IO_URING_SQE;
+	*sqes_ptr_out = mmap(vma2, sqes_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQES);
+
+	return fd_io_uring;
+}
+
+#endif
+
 #if SYZ_EXECUTOR || __NR_syz_io_uring_submit
 
 static long syz_io_uring_submit(volatile long a0, volatile long a1, volatile long a2, volatile long a3)