[Qemu-devel] [PATCH 1/3] linux-user: Allow NULL value pointer in setxattr and getxattr

[Peter Maydell]

It's valid to pass a NULL value pointer to setxattr, so don't
fail this case EFAULT.

Signed-off-by: Peter Maydell <address@hidden>
---
 linux-user/syscall.c |   24 ++++++++++++++++++------
 1 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index f227097..ca4503d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7655,11 +7655,17 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
arg1,
         break;
     case TARGET_NR_setxattr:
         {
-            void *p, *n, *v;
+            void *p, *n, *v = 0;
+            if (arg3) {
+                v = lock_user(VERIFY_READ, arg3, arg4, 1);
+                if (!v) {
+                    ret = -TARGET_EFAULT;
+                    break;
+                }
+            }
             p = lock_user_string(arg1);
             n = lock_user_string(arg2);
-            v = lock_user(VERIFY_READ, arg3, arg4, 1);
-            if (p && n && v) {
+            if (p && n) {
                 ret = get_errno(setxattr(p, n, v, arg4, arg5));
             } else {
                 ret = -TARGET_EFAULT;
@@ -7671,11 +7677,17 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
arg1,
         break;
     case TARGET_NR_getxattr:
         {
-            void *p, *n, *v;
+            void *p, *n, *v = 0;
+            if (arg3) {
+                v = lock_user(VERIFY_WRITE, arg3, arg4, 0);
+                if (!v) {
+                    ret = -TARGET_EFAULT;
+                    break;
+                }
+            }
             p = lock_user_string(arg1);
             n = lock_user_string(arg2);
-            v = lock_user(VERIFY_WRITE, arg3, arg4, 0);
-            if (p && n && v) {
+            if (p && n) {
                 ret = get_errno(getxattr(p, n, v, arg4));
             } else {
                 ret = -TARGET_EFAULT;
-- 
1.7.5.4