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libfdt: Add support for disabling dtb checks

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Support ASSUME_VALID_DTB to disable some sanity checks

If we assume that the DTB itself is valid then we can skip some checks and
save code space. Add various conditions to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Message-Id: <20200220214557.176528-4-sjg@chromium.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Simon Glass 2020-02-20 14:45:52 -07:00 • committed by David Gibson
parent 464962489d
commit 57bc6327b8
4 changed files with 47 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

57
libfdt/fdt.c
View file

@ -19,6 +19,9 @@ int32_t fdt_ro_probe_(const void *fdt)
{
uint32_t totalsize = fdt_totalsize(fdt);
if (can_assume(VALID_DTB))
return totalsize;
if (fdt_magic(fdt) == FDT_MAGIC) {
/* Complete tree */
if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
@ -81,37 +84,43 @@ int fdt_check_header(const void *fdt)
if (fdt_magic(fdt) != FDT_MAGIC)
return -FDT_ERR_BADMAGIC;
hdrsize = fdt_header_size(fdt);
if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
|| (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION))
return -FDT_ERR_BADVERSION;
if (fdt_version(fdt) < fdt_last_comp_version(fdt))
return -FDT_ERR_BADVERSION;
hdrsize = fdt_header_size(fdt);
if (!can_assume(VALID_DTB)) {
if ((fdt_totalsize(fdt) < hdrsize)
|| (fdt_totalsize(fdt) > INT_MAX))
return -FDT_ERR_TRUNCATED;
/* Bounds check memrsv block */
if (!check_off_(hdrsize, fdt_totalsize(fdt), fdt_off_mem_rsvmap(fdt)))
return -FDT_ERR_TRUNCATED;
/* Bounds check structure block */
if (fdt_version(fdt) < 17) {
if (!check_off_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_struct(fdt)))
if ((fdt_totalsize(fdt) < hdrsize)
|| (fdt_totalsize(fdt) > INT_MAX))
return -FDT_ERR_TRUNCATED;
} else {
if (!check_block_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_struct(fdt),
fdt_size_dt_struct(fdt)))
/* Bounds check memrsv block */
if (!check_off_(hdrsize, fdt_totalsize(fdt),
fdt_off_mem_rsvmap(fdt)))
return -FDT_ERR_TRUNCATED;
}
/* Bounds check strings block */
if (!check_block_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_strings(fdt), fdt_size_dt_strings(fdt)))
return -FDT_ERR_TRUNCATED;
if (!can_assume(VALID_DTB)) {
/* Bounds check structure block */
if (fdt_version(fdt) < 17) {
if (!check_off_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_struct(fdt)))
return -FDT_ERR_TRUNCATED;
} else {
if (!check_block_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_struct(fdt),
fdt_size_dt_struct(fdt)))
return -FDT_ERR_TRUNCATED;
}
/* Bounds check strings block */
if (!check_block_(hdrsize, fdt_totalsize(fdt),
fdt_off_dt_strings(fdt),
fdt_size_dt_strings(fdt)))
return -FDT_ERR_TRUNCATED;
}
return 0;
}
@ -142,7 +151,7 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
*nextoffset = -FDT_ERR_TRUNCATED;
tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
if (!tagp)
if (!can_assume(VALID_DTB) && !tagp)
return FDT_END; /* premature end */
tag = fdt32_to_cpu(*tagp);
offset += FDT_TAGSIZE;
@ -154,13 +163,13 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
do {
p = fdt_offset_ptr(fdt, offset++, 1);
} while (p && (*p != '\0'));
if (!p)
if (!can_assume(VALID_DTB) && !p)
return FDT_END; /* premature end */
break;
case FDT_PROP:
lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
if (!lenp)
if (!can_assume(VALID_DTB) && !lenp)
return FDT_END; /* premature end */
/* skip-name offset, length and value */
offset += sizeof(struct fdt_property) - FDT_TAGSIZE

3
libfdt/fdt_ro.c
View file

@ -388,7 +388,8 @@ static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
(offset = fdt_next_property_offset(fdt, offset))) {
const struct fdt_property *prop;
if (!(prop = fdt_get_property_by_offset_(fdt, offset, lenp))) {
prop = fdt_get_property_by_offset_(fdt, offset, lenp);
if (!can_assume(VALID_DTB) && !prop) {
offset = -FDT_ERR_INTERNAL;
break;
}

2
libfdt/fdt_rw.c
View file

@ -24,6 +24,8 @@ static int fdt_blocks_misordered_(const void *fdt,
static int fdt_rw_probe_(void *fdt)
{
if (can_assume(VALID_DTB))
return 0;
FDT_RO_PROBE(fdt);
if (fdt_version(fdt) < 17)

16
libfdt/fdt_sw.c
View file

@ -12,10 +12,13 @@
static int fdt_sw_probe_(void *fdt)
{
if (fdt_magic(fdt) == FDT_MAGIC)
return -FDT_ERR_BADSTATE;
else if (fdt_magic(fdt) != FDT_SW_MAGIC)
return -FDT_ERR_BADMAGIC;
if (!can_assume(VALID_DTB)) {
if (fdt_magic(fdt) == FDT_MAGIC)
return -FDT_ERR_BADSTATE;
else if (fdt_magic(fdt) != FDT_SW_MAGIC)
return -FDT_ERR_BADMAGIC;
}
return 0;
}
@ -38,7 +41,7 @@ static int fdt_sw_probe_memrsv_(void *fdt)
if (err)
return err;
if (fdt_off_dt_strings(fdt) != 0)
if (!can_assume(VALID_DTB) && fdt_off_dt_strings(fdt) != 0)
return -FDT_ERR_BADSTATE;
return 0;
}
@ -151,7 +154,8 @@ int fdt_resize(void *fdt, void *buf, int bufsize)
headsize = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
tailsize = fdt_size_dt_strings(fdt);
if ((headsize + tailsize) > fdt_totalsize(fdt))
if (!can_assume(VALID_DTB) &&
headsize + tailsize > fdt_totalsize(fdt))
return -FDT_ERR_INTERNAL;
if ((headsize + tailsize) > bufsize)