From: Max Filippov <jcmvb...@gmail.com>
setrlimit guest calls that affect memory resources
(RLIMIT_{AS,DATA,STACK}) may interfere with QEMU internal memory
management. They may result in QEMU lockup because mprotect call in
page_unprotect would fail with ENOMEM error code, causing infinite loop
of SIGSEGV. E.g. it happens when running libstdc++ testsuite for xtensa
target on x86_64 host.
Don't call host setrlimit for memory-related resources.
Reviewed-by: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Max Filippov <jcmvb...@gmail.com>
Message-Id: <20180917181314.22551-1-jcmvb...@gmail.com>
[lv: rebase on master]
Signed-off-by: Laurent Vivier <laur...@vivier.eu>
---
linux-user/syscall.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 019af632df..ae3c0dfef7 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7879,7 +7879,21 @@ static abi_long do_syscall1(void *cpu_env, int num,
abi_long arg1,
rlim.rlim_cur = target_to_host_rlim(target_rlim->rlim_cur);
rlim.rlim_max = target_to_host_rlim(target_rlim->rlim_max);
unlock_user_struct(target_rlim, arg2, 0);
- return get_errno(setrlimit(resource, &rlim));
+ /*
+ * If we just passed through resource limit settings for memory
then
+ * they would also apply to QEMU's own allocations, and QEMU will
+ * crash or hang or die if its allocations fail. Ideally we would
+ * track the guest allocations in QEMU and apply the limits
ourselves.
+ * For now, just tell the guest the call succeeded but don't
actually
+ * limit anything.
+ */
+ if (resource != RLIMIT_AS &&
+ resource != RLIMIT_DATA &&
+ resource != RLIMIT_STACK) {
+ return get_errno(setrlimit(resource, &rlim));
+ } else {
+ return 0;
+ }
}
#endif
#ifdef TARGET_NR_getrlimit
--
2.17.1
