grep branch, master, updated. v2.21-18-g3d6cd21

[Jim Meyering]

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http://git.savannah.gnu.org/cgit/grep.git/commit/?id=3d6cd2129e0454c537b315ce0a3aab8e032fa76a


commit 3d6cd2129e0454c537b315ce0a3aab8e032fa76a
Author: Jim Meyering <address@hidden>
Date:   Wed Feb 11 12:12:23 2015 -0800

    maint: use ASAN-poisoning more carefully
    
    The ASAN-poisoning instituted by commit v2.21-14-g1555185 was
    incomplete, since the poisoned tail of the read buffer could well
    be the target of a legitimate follow-on read.  To accommodate that,
    we must unpoison each such region just before beginning fillbuf's
    read loop.
    * src/grep.c [HAVE_ASAN] (asan_poison): Define.
    (clear_asan_poison): Define.
    (fillbuf): Clear before reading, since we are likely to read
    into memory that was poisoned on the preceding iteration.
    * tests/two-files: New file, to test for this.
    * tests/Makefile.am (TESTS): Add it.

diff --git a/src/grep.c b/src/grep.c
index 7d70f4a..f720a8a 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -80,6 +80,32 @@ static bool only_matching;
 /* If nonzero, make sure first content char in a line is on a tab stop. */
 static bool align_tabs;
 
+#if HAVE_ASAN
+/* Record the starting address and length of the sole poisoned region,
+   so that we can unpoison it later, just before each following read.  */
+static void const *poison_buf;
+static size_t poison_len;
+
+static void
+clear_asan_poison (void)
+{
+  if (poison_buf)
+    __asan_unpoison_memory_region (poison_buf, poison_len);
+}
+
+static void
+asan_poison (void const *addr, size_t size)
+{
+  poison_buf = addr;
+  poison_len = size;
+
+  __asan_poison_memory_region (poison_buf, poison_len);
+}
+#else
+static void clear_asan_poison (void) { }
+static void asan_poison (void const volatile *addr, size_t size) { }
+#endif
+
 /* The group separator used when context is requested. */
 static const char *group_separator = SEP_STR_GROUP;
 
@@ -773,6 +799,8 @@ fillbuf (size_t save, struct stat const *st)
         }
     }
 
+  clear_asan_poison ();
+
   readsize = buffer + bufalloc - sizeof (uword) - readbuf;
   readsize -= readsize % pagesize;
 
@@ -818,8 +846,8 @@ fillbuf (size_t save, struct stat const *st)
 
   /* Mark the part of the buffer not filled by the read or set by
      the above memset call as ASAN-poisoned.  */
-  __asan_poison_memory_region (buflim + sizeof (uword),
-                               bufalloc - (buflim - buffer) - sizeof (uword));
+  asan_poison (buflim + sizeof (uword),
+               bufalloc - (buflim - buffer) - sizeof (uword));
 
   return cc;
 }
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8fcf8f6..33b6adc 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -114,6 +114,7 @@ TESTS =                                             \
   surrogate-pair                               \
   symlink                                      \
   triple-backref                               \
+  two-files                                    \
   turkish-eyes                                 \
   turkish-I                                    \
   turkish-I-without-dot                                \
diff --git a/tests/two-files b/tests/two-files
new file mode 100755
index 0000000..d655e56
--- /dev/null
+++ b/tests/two-files
@@ -0,0 +1,22 @@
+#! /bin/sh
+# Read two files, of increasing size.
+# With ASAN, this would have triggered a false-positive read of poisoned 
memory.
+#
+# Copyright 2015 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# are permitted in any medium without royalty provided the copyright
+# notice and this notice are preserved.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+
+fail=0
+
+printf a > 1 || framework_failure_
+printf ab > 2 || framework_failure_
+
+grep x 1 2 > out 2>&1
+test $? -eq 1 || fail=1
+compare /dev/null out || fail=1
+
+Exit $fail

-----------------------------------------------------------------------

Summary of changes:
 src/grep.c                      |   32 ++++++++++++++++++++++++++++++--
 tests/Makefile.am               |    1 +
 tests/{pcre-abort => two-files} |   15 ++++++++-------
 3 files changed, 39 insertions(+), 9 deletions(-)
 copy tests/{pcre-abort => two-files} (50%)


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