[Qemu-devel] [PATCH v2] linux-user: do setrlimit selectively

[Max Filippov]

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.

Signed-off-by: Max Filippov <address@hidden>
---
Changes v1->v2:
- don't limit change to 32-bit guest on 64-bit host case

 linux-user/syscall.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index bb42a225eb58..a9cace49dad8 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -9275,7 +9275,13 @@ abi_long do_syscall(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);
-            ret = get_errno(setrlimit(resource, &rlim));
+            if (resource != RLIMIT_AS &&
+                resource != RLIMIT_DATA &&
+                resource != RLIMIT_STACK) {
+                return get_errno(setrlimit(resource, &rlim));
+            } else {
+                return 0;
+            }
         }
         break;
 #endif
-- 
2.11.0