Fixed google::FindSymbol reading past end of a section

base/third_party/symbolize/symbolize.cc

Index: base/third_party/symbolize/symbolize.cc
diff --git a/base/third_party/symbolize/symbolize.cc b/base/third_party/symbolize/symbolize.cc
index d7678956c87f603eb1b0483bb819a9f401ca2dc2..9e081ce7f4133c126e4c957b829954da54badca7 100644
--- a/base/third_party/symbolize/symbolize.cc
+++ b/base/third_party/symbolize/symbolize.cc
@@ -296,10 +296,14 @@ FindSymbol(uint64_t pc, const int fd, char *out, int out_size,
 
     // Read at most NUM_SYMBOLS symbols at once to save read() calls.
     ElfW(Sym) buf[NUM_SYMBOLS];
-    const ssize_t len = ReadFromOffset(fd, &buf, sizeof(buf), offset);
+    int num_symbols_to_read = num_symbols - i;

[hamaji, 2016/12/16 07:21:14]

Use std::min?

+    if (num_symbols_to_read > NUM_SYMBOLS)
+      num_symbols_to_read = NUM_SYMBOLS;
+    const ssize_t len =
+        ReadFromOffset(fd, &buf, sizeof(buf[0]) * num_symbols_to_read, offset);
     SAFE_ASSERT(len % sizeof(buf[0]) == 0);
     const ssize_t num_symbols_in_buf = len / sizeof(buf[0]);
-    SAFE_ASSERT(num_symbols_in_buf <= sizeof(buf)/sizeof(buf[0]));
+    SAFE_ASSERT(num_symbols_in_buf <= num_symbols_to_read);
     for (int j = 0; j < num_symbols_in_buf; ++j) {
       const ElfW(Sym)& symbol = buf[j];
       uint64_t start_address = symbol.st_value;