H5O_fsinfo_decode() Make more resilient to out-of-bounds read

Malformed hdf5 files may have trunkated content which does not match
the expected size. This function attempts to decode these it will read
past the end of the allocated space which may lead to a crash. Make sure
each element is within bounds before reading.

This fixes CVE-2021-45830 / Bug HDFGroup#2228.

Signed-off-by: Egbert Eich <eich@suse.com>

Additions

src/H5Ofsinfo.c

@@ -88,6 +88,7 @@ H5FL_DEFINE_STATIC(H5O_fsinfo_t);
  *
  *-------------------------------------------------------------------------
  */
+
 static void *
 H5O__fsinfo_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNUSED mesg_flags,
                    unsigned H5_ATTR_UNUSED *ioflags, size_t p_size, const uint8_t *p)
@@ -112,6 +113,8 @@ H5O__fsinfo_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNU
         fsinfo->fs_addr[ptype - 1] = HADDR_UNDEF;
 
     /* Version of message */
+    if (p + 1 - 1 > p_end) /* one byte for version */
+        HGOTO_ERROR(H5E_OHDR, H5E_NOSPACE, NULL, "ran off end of input buffer while decoding")
     vers = *p++;
 
     if (vers == H5O_FSINFO_VERSION_0) {
@@ -125,6 +128,8 @@ H5O__fsinfo_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNU
         fsinfo->pgend_meta_thres    = H5F_FILE_SPACE_PGEND_META_THRES;
         fsinfo->eoa_pre_fsm_fsalloc = HADDR_UNDEF;
 
+        if (p + 1 + H5F_SIZEOF_SIZE(f) - 1 > p_end) /* one byte for strategy + sizeof(f)  */
+            HGOTO_ERROR(H5E_OHDR, H5E_NOSPACE, NULL, "ran off end of input buffer while decoding")
         strategy = (H5F_file_space_type_t)*p++; /* File space strategy */
         H5F_DECODE_LENGTH(f, p, threshold);     /* Free-space section threshold */
 
@@ -169,7 +174,10 @@ H5O__fsinfo_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNU
     else {
         HDassert(vers >= H5O_FSINFO_VERSION_1);
 
-        fsinfo->version  = vers;
+        fsinfo->version = vers;
+        /* strategy (1) + persist (1) + sizeof(f) + sizeof(f) + pgend_meta_thres (2)  + sizeofaddr(f) */
+        if (p + 1 + 1 + 2 * H5F_SIZEOF_SIZE(f) + 2 + H5F_SIZEOF_ADDR(f) - 1 > p_end)
+            HGOTO_ERROR(H5E_OHDR, H5E_NOSPACE, NULL, "ran off end of input buffer while decoding")
         fsinfo->strategy = (H5F_fspace_strategy_t)*p++; /* File space strategy */
         fsinfo->persist  = *p++;                        /* Free-space persist or not */
         H5F_DECODE_LENGTH(f, p, fsinfo->threshold);     /* Free-space section threshold */
@@ -181,9 +189,11 @@ H5O__fsinfo_decode(H5F_t *f, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNU
 
         /* Decode addresses of free space managers, if persisting */
         if (fsinfo->persist)
-            for (ptype = H5F_MEM_PAGE_SUPER; ptype < H5F_MEM_PAGE_NTYPES; ptype++)
+            for (ptype = H5F_MEM_PAGE_SUPER; ptype < H5F_MEM_PAGE_NTYPES; ptype++) {
+                if (p + H5F_SIZEOF_SIZE(f) - 1 > p_end) /* one byte for sizeof(f)  */
+                    HGOTO_ERROR(H5E_OHDR, H5E_NOSPACE, NULL, "ran off end of input buffer while decoding")
                 H5F_addr_decode(f, &p, &(fsinfo->fs_addr[ptype - 1]));
-
+            }
         fsinfo->mapped = FALSE;
     }