Currently, callers of fdt_next_tag() must usually follow the call with some sort of call to fdt_offset_ptr() to verify that the blob isn't truncated in the middle of the tag data they're going to process. This is a bit silly, since fdt_next_tag() generally has to call fdt_offset_ptr() on at least some of the data following the tag for its own operation.
This patch alters fdt_next_tag() to always use fdt_offset_ptr() to verify the data between its starting offset and the offset it returns in nextoffset. This simplifies fdt_get_property() which no longer has to verify itself that the property data is all present.
At the same time, I neaten and clarify the error handling for fdt_next_tag(). Previously, fdt_next_tag() could return -1 instead of a tag value in some circumstances - which almost none of the callers checked for. Also, fdt_next_tag() could return FDT_END either because it encountered an FDT_END tag, or because it reached the end of the structure block - no way was provided to tell between these cases.
With this patch, fdt_next_tag() always returns FDT_END with a negative value in nextoffset for an error. This means the several places which loop looking for FDT_END will still work correctly - they only need to check for errors at the end. The errors which fdt_next_tag() can report are: - -FDT_ERR_TRUNCATED if it reached the end of the structure block instead of finding a tag.
- -FDT_BADSTRUCTURE if a bad tag was encountered, or if the tag data couldn't be verified with fdt_offset_ptr().
This patch also updates the callers of fdt_next_tag(), where appropriate, to make use of the new error reporting.
Finally, the prototype for the long gone _fdt_next_tag() is removed from libfdt_internal.h.
Signed-off-by: David Gibson david@gibson.dropbear.id.au --- libfdt/fdt.c | 46 +++++++++++++++++++++++++++++----------------- libfdt/fdt_ro.c | 33 +++++++++------------------------ libfdt/fdt_rw.c | 2 ++ libfdt/fdt_sw.c | 9 ++++----- libfdt/libfdt_internal.h | 1 - 5 files changed, 44 insertions(+), 47 deletions(-)
diff --git a/libfdt/fdt.c b/libfdt/fdt.c index 940cee8..b09ea6f 100644 --- a/libfdt/fdt.c +++ b/libfdt/fdt.c @@ -94,42 +94,53 @@ const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len) return p; }
-uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset) +uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset) { const uint32_t *tagp, *lenp; uint32_t tag; + int offset = startoffset; const char *p;
- if (offset % FDT_TAGSIZE) - return -1; - + *nextoffset = -FDT_ERR_TRUNCATED; tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE); - if (! tagp) + if (!tagp) return FDT_END; /* premature end */ tag = fdt32_to_cpu(*tagp); offset += FDT_TAGSIZE;
+ *nextoffset = -FDT_ERR_BADSTRUCTURE; switch (tag) { case FDT_BEGIN_NODE: /* skip name */ do { p = fdt_offset_ptr(fdt, offset++, 1); } while (p && (*p != '\0')); - if (! p) - return FDT_END; + if (!p) + return FDT_END; /* premature end */ break; + case FDT_PROP: lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp)); - if (! lenp) - return FDT_END; - /* skip name offset, length and value */ - offset += 2*FDT_TAGSIZE + fdt32_to_cpu(*lenp); + if (!lenp) + return FDT_END; /* premature end */ + /* skip-name offset, length and value */ + offset += sizeof(struct fdt_property) - FDT_TAGSIZE + + fdt32_to_cpu(*lenp); + break; + + case FDT_END: + case FDT_END_NODE: + case FDT_NOP: break; + + default: + return FDT_END; }
- if (nextoffset) - *nextoffset = FDT_TAGALIGN(offset); + if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset)) + return FDT_END; /* premature end */
+ *nextoffset = FDT_TAGALIGN(offset); return tag; }
@@ -171,10 +182,11 @@ int fdt_next_node(const void *fdt, int offset, int *depth) break;
case FDT_END: - return -FDT_ERR_NOTFOUND; - - default: - return -FDT_ERR_BADSTRUCTURE; + if ((nextoffset >= 0) + || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth)) + return -FDT_ERR_NOTFOUND; + else + return nextoffset; } } while (tag != FDT_BEGIN_NODE);
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c index d682a40..1e1e322 100644 --- a/libfdt/fdt_ro.c +++ b/libfdt/fdt_ro.c @@ -205,7 +205,6 @@ const struct fdt_property *fdt_get_property_namelen(const void *fdt, { uint32_t tag; const struct fdt_property *prop; - int namestroff; int offset, nextoffset; int err;
@@ -220,38 +219,24 @@ const struct fdt_property *fdt_get_property_namelen(const void *fdt, tag = fdt_next_tag(fdt, offset, &nextoffset); switch (tag) { case FDT_END: - err = -FDT_ERR_TRUNCATED; + if (nextoffset < 0) + err = nextoffset; + else + /* FDT_END tag with unclosed nodes */ + err = -FDT_ERR_BADSTRUCTURE; goto fail;
- case FDT_BEGIN_NODE: - case FDT_END_NODE: - case FDT_NOP: - break; - case FDT_PROP: - err = -FDT_ERR_BADSTRUCTURE; - prop = fdt_offset_ptr(fdt, offset, sizeof(*prop)); - if (! prop) - goto fail; - namestroff = fdt32_to_cpu(prop->nameoff); - if (_fdt_string_eq(fdt, namestroff, name, namelen)) { + prop = _fdt_offset_ptr(fdt, offset); + if (_fdt_string_eq(fdt, fdt32_to_cpu(prop->nameoff), + name, namelen)) { /* Found it! */ - int len = fdt32_to_cpu(prop->len); - prop = fdt_offset_ptr(fdt, offset, - sizeof(*prop)+len); - if (! prop) - goto fail; - if (lenp) - *lenp = len; + *lenp = fdt32_to_cpu(prop->len);
return prop; } break; - - default: - err = -FDT_ERR_BADSTRUCTURE; - goto fail; } } while ((tag != FDT_BEGIN_NODE) && (tag != FDT_END_NODE));
diff --git a/libfdt/fdt_rw.c b/libfdt/fdt_rw.c index cd06178..5c27a67 100644 --- a/libfdt/fdt_rw.c +++ b/libfdt/fdt_rw.c @@ -410,6 +410,8 @@ int fdt_open_into(const void *fdt, void *buf, int bufsize) struct_size = 0; while (fdt_next_tag(fdt, struct_size, &struct_size) != FDT_END) ; + if (struct_size < 0) + return struct_size; }
if (!_fdt_blocks_misordered(fdt, mem_rsv_size, struct_size)) { diff --git a/libfdt/fdt_sw.c b/libfdt/fdt_sw.c index 698329e..2380b27 100644 --- a/libfdt/fdt_sw.c +++ b/libfdt/fdt_sw.c @@ -82,7 +82,7 @@ static void *_fdt_grab_space(void *fdt, int len) return NULL;
fdt_set_size_dt_struct(fdt, offset + len); - return fdt_offset_ptr_w(fdt, offset, len); + return _fdt_offset_ptr_w(fdt, offset); }
int fdt_create(void *buf, int bufsize) @@ -237,18 +237,17 @@ int fdt_finish(void *fdt) while ((tag = fdt_next_tag(fdt, offset, &nextoffset)) != FDT_END) { if (tag == FDT_PROP) { struct fdt_property *prop = - fdt_offset_ptr_w(fdt, offset, sizeof(*prop)); + _fdt_offset_ptr_w(fdt, offset); int nameoff;
- if (! prop) - return -FDT_ERR_BADSTRUCTURE; - nameoff = fdt32_to_cpu(prop->nameoff); nameoff += fdt_size_dt_strings(fdt); prop->nameoff = cpu_to_fdt32(nameoff); } offset = nextoffset; } + if (nextoffset < 0) + return nextoffset;
/* Finally, adjust the header */ fdt_set_totalsize(fdt, newstroffset + fdt_size_dt_strings(fdt)); diff --git a/libfdt/libfdt_internal.h b/libfdt/libfdt_internal.h index 46eb93e..d2dcbd6 100644 --- a/libfdt/libfdt_internal.h +++ b/libfdt/libfdt_internal.h @@ -62,7 +62,6 @@ return err; \ }
-uint32_t _fdt_next_tag(const void *fdt, int startoffset, int *nextoffset); int _fdt_check_node_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);