[Qemu-devel] [PATCH] linux-user: Handle brk() attempts with very large sizes

[Peter Maydell <peter.maydell@linaro.org>]

In do_brk(), we were inadvertently truncating the size
of a requested brk() from the guest by putting it into an
'int' variable. This meant that we would incorrectly report
success back to the guest rather than a failed allocation,
typically resulting in the guest then segfaulting. Use
abi_ulong instead.

This fixes a crash in the '31370.cc' test in the gcc libstdc++ test
suite (the test case starts by trying to allocate a very large
size and reduces the size until the allocation succeeds).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 linux-user/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index b4dc721..0e98593 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -830,7 +830,7 @@ void target_set_brk(abi_ulong new_brk)
 abi_long do_brk(abi_ulong new_brk)
 {
     abi_long mapped_addr;
-    int	new_alloc_size;
+    abi_ulong new_alloc_size;
 
     DEBUGF_BRK("do_brk(" TARGET_ABI_FMT_lx ") -> ", new_brk);
 
-- 
1.9.1