Bug 401284 - False positive "Source and destination overlap in strncat"

Need to also look at strlcat and plain strcat.

diff --git a/.gitignore b/.gitignore
index da322ecf1d294ad8da0287b149a333d799a116aa..5090d773b5df74291ca42663fd8ae0fbd1f95295 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -857,6 +857,7 @@
 /memcheck/tests/bug340392
 /memcheck/tests/bug464969_d_demangle
 /memcheck/tests/bug472219
+/memcheck/tests/bug401284
 /memcheck/tests/calloc-overflow
 /memcheck/tests/cdebug_zlib
 /memcheck/tests/cdebug_zlib_gnu

diff --git a/NEWS b/NEWS
index 5b62d05260582a879b900b150b1b27040a5da1ed..05fb4a8ddc8ab03e305525a152011d6c9ad995ee 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -23,6 +23,8 @@ bugzilla (https://bugs.kde.org/enter_bug.cgi?product=valgrind) rather
 than mailing the developers (or mailing lists) directly -- bugs that
 are not entered into bugzilla tend to get forgotten about or ignored.
 
+
+401284  False positive "Source and destination overlap in strncat"
 475498  Add reallocarray wrapper
 476320  Build failure with GCC
 476535  Difference in allocation size for massif/tests/overloaded-new between clang++/libc++ and g++/libstdc++

diff --git a/memcheck/tests/Makefile.am b/memcheck/tests/Makefile.am
index 47b5384742634cd1eb63a3a7768024af6f8e894d..e49888be81416ed5be1d2380720a2bd330bda6ce 100644 (file)
--- a/memcheck/tests/Makefile.am
+++ b/memcheck/tests/Makefile.am
@@ -97,10 +97,6 @@ EXTRA_DIST = \
        atomic_incs.stdout.exp-64bit-and-128bit \
        badaddrvalue.stderr.exp \
        badaddrvalue.stdout.exp badaddrvalue.vgtest \
-        exit_on_first_error.stderr.exp \
-        exit_on_first_error.vgtest \
-        exit_on_first_error_with_xml.stderr.exp \
-        exit_on_first_error_with_xml.vgtest \
        badfree-2trace.stderr.exp badfree-2trace.vgtest \
        badfree.stderr.exp badfree.vgtest \
        badfree3.stderr.exp badfree3.vgtest \
@@ -118,6 +114,7 @@ EXTRA_DIST = \
        bug155125.stderr.exp bug155125.vgtest \
        bug287260.stderr.exp bug287260.vgtest \
        bug340392.stderr.exp bug340392.vgtest \
+       bug401284.stderr.exp bug401284.stdout.exp bug401284.vgtest \
        bug464969_d_demangle.stderr.exp bug464969_d_demangle.vgtest \
                bug464969_d_demangle.stdout.exp \
        bug472219.stderr.exp bug472219.vgtest \
@@ -195,6 +192,10 @@ EXTRA_DIST = \
        erringfds.stderr.exp erringfds.stdout.exp erringfds.vgtest \
        error_counts.stderr.exp error_counts.vgtest \
        errs1.stderr.exp errs1.vgtest \
+        exit_on_first_error.stderr.exp \
+        exit_on_first_error.vgtest \
+        exit_on_first_error_with_xml.stderr.exp \
+        exit_on_first_error_with_xml.vgtest \
        exitprog.stderr.exp exitprog.vgtest \
        execve1.stderr.exp execve1.vgtest execve1.stderr.exp-kfail \
        execve2.stderr.exp execve2.vgtest execve2.stderr.exp-kfail \
@@ -457,6 +458,7 @@ check_PROGRAMS = \
        bug155125 \
        bug287260 \
        bug340392 \
+       bug401284 \
        bug464969_d_demangle \
        bug472219 \
        calloc-overflow \

diff --git a/memcheck/tests/bug401284.c b/memcheck/tests/bug401284.c
new file mode 100644 (file)
index 0000000..704ed52
--- /dev/null
+++ b/memcheck/tests/bug401284.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char* argv[])
+{
+    size_t len = strlen(argv[1]);
+    char*  buf = (char*) malloc(2 * len + 1);
+    memcpy(buf, argv[1], len + 1);
+    strncat(buf + len, buf, len);
+    printf("%s\n", buf);
+    free(buf);
+    return 0;
+}

diff --git a/memcheck/tests/bug401284.stderr.exp b/memcheck/tests/bug401284.stderr.exp
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/memcheck/tests/bug401284.stdout.exp b/memcheck/tests/bug401284.stdout.exp
new file mode 100644 (file)
index 0000000..9c708c1
--- /dev/null
+++ b/memcheck/tests/bug401284.stdout.exp
@@ -0,0 +1 @@
+hellohello

diff --git a/memcheck/tests/bug401284.vgtest b/memcheck/tests/bug401284.vgtest
new file mode 100644 (file)
index 0000000..d846d21
--- /dev/null
+++ b/memcheck/tests/bug401284.vgtest
@@ -0,0 +1,3 @@
+prog: bug401284
+args: hello
+vgopts: -q

diff --git a/shared/vg_replace_strmem.c b/shared/vg_replace_strmem.c
index 79e640189f2e11ee2bfcb3f16f5dae04b011d74e..747b903fefd93530779fe33115ee26c234d4c635 100644 (file)
--- a/shared/vg_replace_strmem.c
+++ b/shared/vg_replace_strmem.c
@@ -370,7 +370,7 @@ static inline void my_exit ( int x )
       if (is_overlap(dst_orig,  \
                      src_orig,  \
                      (Addr)dst-(Addr)dst_orig+1, \
-                     (Addr)src-(Addr)src_orig+1)) \
+                     (Addr)src-(Addr)src_orig)) \
          RECORD_OVERLAP_ERROR("strncat", dst_orig, src_orig, n); \
       \
       return dst_orig; \