Fix BZ #342683. Based on patch by Ivo Raisr.
What this does is to make sure that the initial client data segment
is marked as unaddressable. This is consistent with the behaviour of
brk when the data segment is shrunk. The "freed" memory is marked
as unaddressable.
Special tweaks were needed for s390 which was returning early from
the funtion to avoid sloppy register definedness initialisation.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15144 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/NEWS b/NEWS
index 2a61168..71e0755 100644
--- a/NEWS
+++ b/NEWS
@@ -108,6 +108,7 @@
342353 Allow dumping full massif output while valgrind is still running
342603 Add I2C_SMBUS ioctl support
342635 OS X 10.10 (Yosemite) - missing system calls and fcntl code
+342683 Mark memory past the initial brk limit as unaddressable
342795 Internal glibc __GI_mempcpy call should be intercepted
343012 Unhandled syscall 319 (memfd_create)
343069 Patch updating v4l2 API support
diff --git a/coregrind/m_initimg/initimg-linux.c b/coregrind/m_initimg/initimg-linux.c
index 868325b..64b404f 100644
--- a/coregrind/m_initimg/initimg-linux.c
+++ b/coregrind/m_initimg/initimg-linux.c
@@ -1143,7 +1143,12 @@
VG_TRACK(post_reg_write, Vg_CoreStartup, /*tid*/1, VG_O_STACK_PTR, 8);
VG_TRACK(post_reg_write, Vg_CoreStartup, /*tid*/1, VG_O_FPC_REG, 4);
VG_TRACK(post_reg_write, Vg_CoreStartup, /*tid*/1, VG_O_INSTR_PTR, 8);
- return;
+
+ /* At the end of this function there is code to mark all guest state
+ registers as defined. For s390 that would be wrong, because the ABI
+ says that all registers except SP, IA, and FPC are undefined upon
+ process startup. */
+#define PRECISE_GUEST_REG_DEFINEDNESS_AT_STARTUP 1
# elif defined(VGP_mips32_linux)
vg_assert(0 == sizeof(VexGuestMIPS32State) % 16);
@@ -1192,9 +1197,20 @@
# error Unknown platform
# endif
+# if !defined(PRECISE_GUEST_REG_DEFINEDNESS_AT_STARTUP)
/* Tell the tool that we just wrote to the registers. */
VG_TRACK( post_reg_write, Vg_CoreStartup, /*tid*/1, /*offset*/0,
sizeof(VexGuestArchState));
+# endif
+
+ /* Tell the tool about the client data segment and then kill it which will
+ make it inaccessible/unaddressable. */
+ const NSegment *seg = VG_(am_find_nsegment)(VG_(brk_base));
+ vg_assert(seg);
+ vg_assert(seg->kind == SkAnonC);
+ VG_TRACK(new_mem_brk, VG_(brk_base), seg->end + 1 - VG_(brk_base),
+ 1/*tid*/);
+ VG_TRACK(die_mem_brk, VG_(brk_base), seg->end + 1 - VG_(brk_base));
}
#endif // defined(VGO_linux)
diff --git a/memcheck/tests/dw4.stderr.exp b/memcheck/tests/dw4.stderr.exp
index e396a43..917dcb5 100644
--- a/memcheck/tests/dw4.stderr.exp
+++ b/memcheck/tests/dw4.stderr.exp
@@ -27,8 +27,8 @@
by 0x........: main (dw4.c:82)
Address 0x........ is in a rw- mapped file valgrind-dw4-test.PID segment
-Uninitialised byte(s) found during client check request
- at 0x........: croak (dw4.c:32)
+Unaddressable byte(s) found during client check request
+ at 0x........: croak (dw4.c:25)
by 0x........: main (dw4.c:87)
Address 0x........ is 0 bytes after the brk data segment limit 0x........
