commit 84b968f1ee85e65c1c2a2f8bf0120240247c379c
author Sami Tolvanen <samitolvanen@google.com> Wed Oct 19 15:58:13 2016 -0700
committer gitbuildkicker <android-build@google.com> Fri Oct 21 14:05:26 2016 -0700
tree 1e9dd8f88fec55c981791b119efa91aaa7587d0c
parent 9035e9b38a892f77d0071f70f3b4be9cd5bba2f8

libfec: correct verity table only if it's invalid

To increase reliability in the case where part of the partition is
corrupt and error correction might fail, attempt to use raw verity
table before the corrected one.

Bug: 32288104
Test: tested on angler
Change-Id: I201fdc6162c87b1808979486df5707d683a6d20c
(cherry picked from commit b5afa97f093e0b87614cb9e96a754f7c0e169c4f)

libfec/fec_verity.cpp

diff --git a/libfec/fec_verity.cpp b/libfec/fec_verity.cpp
index 5dea53d..3f636dd 100644
--- a/libfec/fec_verity.cpp
+++ b/libfec/fec_verity.cpp
@@ -312,6 +312,11 @@
 
     debug("valid");
 
+    if (v->hash) {
+        delete[] v->hash;
+        v->hash = NULL;
+    }
+
     v->hash = data_hashes.release();
     return 0;
 }
@@ -319,7 +324,7 @@
 /* reads, corrects and parses the verity table, validates parameters, and if
    `f->flags' does not have `FEC_VERITY_DISABLE' set, calls `verify_tree' to
    load and validate the hash tree */
-static int parse_table(fec_handle *f, uint64_t offset, uint32_t size)
+static int parse_table(fec_handle *f, uint64_t offset, uint32_t size, bool useecc)
 {
     check(f);
     check(size >= VERITY_MIN_TABLE_SIZE);
@@ -335,8 +340,13 @@
         return -1;
     }
 
-    if (fec_pread(f, table.get(), size, offset) != (ssize_t)size) {
-        error("failed to read verity table: %s", strerror(errno));
+    if (!useecc) {
+        if (!raw_pread(f, table.get(), size, offset)) {
+            error("failed to read verity table: %s", strerror(errno));
+            return -1;
+        }
+    } else if (fec_pread(f, table.get(), size, offset) != (ssize_t)size) {
+        error("failed to ecc read verity table: %s", strerror(errno));
         return -1;
     }
 
@@ -430,7 +440,18 @@
         check(v->data_blocks == v->hash_start / FEC_BLOCKSIZE);
     }
 
+    if (v->salt) {
+        delete[] v->salt;
+        v->salt = NULL;
+    }
+
     v->salt = salt.release();
+
+    if (v->table) {
+        delete[] v->table;
+        v->table = NULL;
+    }
+
     v->table = table.release();
 
     if (!(f->flags & FEC_VERITY_DISABLE)) {
@@ -589,7 +610,10 @@
 
     v->metadata_start = offset;
 
-    if (parse_table(f, offset + sizeof(v->header), v->header.length) == -1) {
+    if (parse_table(f, offset + sizeof(v->header), v->header.length,
+            false) == -1 &&
+        parse_table(f, offset + sizeof(v->header), v->header.length,
+            true)  == -1) {
         return -1;
     }