platform_external_dtc/libfdt/libfdt_internal.h
David Gibson 812b1956a0 libfdt: Tweak data handling to satisfy Coverity
In libfdt we often sanity test fdt_totalsize(fdt) fairly early, then
trust it (but *only* that header field) for the remainder of our work.
However, Coverity gets confused by this - it sees the byteswap in
fdt32_ld() and assumes that means it is coming from an untrusted source
everytime, resulting in many tainted data warnings.

Most of these end up with logic in fdt_get_string() as the unsafe
destination for this tainted data, so let's tweak the logic there to make
it clearer to Coverity that this is ok.

We add a sanity test on fdt_totalsize() to fdt_probe_ro_().  Because the
interface allows bare ints to be used for offsets, we already have the
assumption that totalsize must be 31-bits or less (2GiB would be a
ludicrously large fdt).  This makes this more explicit.

We also make fdt_probe_ro() return the size for convenience, and change the
logic in fdt_get_string() to keep it in a local so that Coverity can see
that it has already been bounds-checked.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2019-07-05 15:31:12 +10:00

51 lines
1.4 KiB
C

/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */
#ifndef LIBFDT_INTERNAL_H
#define LIBFDT_INTERNAL_H
/*
* libfdt - Flat Device Tree manipulation
* Copyright (C) 2006 David Gibson, IBM Corporation.
*/
#include <fdt.h>
#define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
#define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE))
int fdt_ro_probe_(const void *fdt);
#define FDT_RO_PROBE(fdt) \
{ \
int totalsize_; \
if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \
return totalsize_; \
}
int fdt_check_node_offset_(const void *fdt, int offset);
int fdt_check_prop_offset_(const void *fdt, int offset);
const char *fdt_find_string_(const char *strtab, int tabsize, const char *s);
int fdt_node_end_offset_(void *fdt, int nodeoffset);
static inline const void *fdt_offset_ptr_(const void *fdt, int offset)
{
return (const char *)fdt + fdt_off_dt_struct(fdt) + offset;
}
static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
{
return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
}
static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n)
{
const struct fdt_reserve_entry *rsv_table =
(const struct fdt_reserve_entry *)
((const char *)fdt + fdt_off_mem_rsvmap(fdt));
return rsv_table + n;
}
static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n)
{
return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n);
}
#define FDT_SW_MAGIC (~FDT_MAGIC)
#endif /* LIBFDT_INTERNAL_H */