[gcc r14-3609] libstdc++: Do not allow chrono::parse to overflow for %C [PR111162]

[gcc r14-3609] libstdc++: Do not allow chrono::parse to overflow for %C [PR111162]

[Jonathan Wakely]

https://gcc.gnu.org/g:207c507499d23f0176cbfdfe96d3cd50dec39584

commit r14-3609-g207c507499d23f0176cbfdfe96d3cd50dec39584
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Aug 29 13:07:21 2023 +0100

    libstdc++: Do not allow chrono::parse to overflow for %C [PR111162]
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/111162
            * include/bits/chrono_io.h (_Parser::Operator()): Check %C
            values are in range of year::min() to year::max().
            * testsuite/std/time/parse.cc: Check out of range centuries.

Diff:
---
 libstdc++-v3/include/bits/chrono_io.h    |  9 ++++++++-
 libstdc++-v3/testsuite/std/time/parse.cc | 12 ++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index d558802e7d86..f359571b4dba 100644
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -3171,7 +3171,14 @@ namespace __detail
 		    {
 		      auto __v = __read_signed(__num ? __num : 2);
 		      if (!__is_failed(__err))
-			__century = __v * 100;
+			{
+			  int __cmin = (int)year::min() / 100;
+			  int __cmax = (int)year::max() / 100;
+			  if (__cmin <= __v && __v <= __cmax)
+			    __century = __v * 100;
+			  else
+			    __century = -2; // This prevents guessing century.
+			}
 		    }
 		  else if (__mod == 'E')
 		    {
diff --git a/libstdc++-v3/testsuite/std/time/parse.cc b/libstdc++-v3/testsuite/std/time/parse.cc
index 9b36c5d7db4c..46eb7f28c85e 100644
--- a/libstdc++-v3/testsuite/std/time/parse.cc
+++ b/libstdc++-v3/testsuite/std/time/parse.cc
@@ -251,6 +251,18 @@ test_errors()
   is >> parse("%H:%M %3y", y); // 61min is out of range but not needed
   VERIFY( is.eof() && ! is.fail() );
   VERIFY( y == 2010y );
+
+  is.clear();
+  is.str("328 00");
+  is >> parse("%3C %y", y); // 328 is out of range for %C (PR libstdc++/111162)
+  VERIFY( is.fail() );
+  VERIFY( y == 2010y );
+
+  is.clear();
+  is.str("-328 00");
+  is >> parse("%3C %y", y); // -328 is out of range for %C
+  VERIFY( is.fail() );
+  VERIFY( y == 2010y );
 }
 
 void