[Qemu-devel] [patch] fix getgroups and getgroups32 syscalls

["Lauro Ramos Venancio" <lauro.venancio@gmail.com>]

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The attached patch fixes a bug in getgroups and getgroups32 syscalls.
The current implementation returns error when size=0.

According the manual:
" If size is zero, list is not modified, but the total number of
supplementary group IDs for the process is returned."

--
Lauro Ramos Venancio
OpenBossa Labs - Instituto Nokia de Tecnologia
Recife - Brazil

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Index: qemu-arm-eabi/linux-user/syscall.c
===================================================================
--- qemu-arm-eabi.orig/linux-user/syscall.c	2007-12-07 19:59:03.000000000 -0300
+++ qemu-arm-eabi/linux-user/syscall.c	2007-12-07 20:01:47.000000000 -0300
@@ -5024,12 +5024,13 @@
         {
             int gidsetsize = arg1;
             uint16_t *target_grouplist;
-            gid_t *grouplist;
+            gid_t *grouplist = NULL;
             int i;
 
-            grouplist = alloca(gidsetsize * sizeof(gid_t));
+            if (gidsetsize)
+                grouplist = alloca(gidsetsize * sizeof(gid_t));
             ret = get_errno(getgroups(gidsetsize, grouplist));
-            if (!is_error(ret)) {
+            if (gidsetsize && !is_error(ret)) {
                 target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize * 2, 0);
                 if (!target_grouplist)
                     goto efault;
@@ -5174,12 +5175,13 @@
         {
             int gidsetsize = arg1;
             uint32_t *target_grouplist;
-            gid_t *grouplist;
+            gid_t *grouplist = NULL;
             int i;
 
-            grouplist = alloca(gidsetsize * sizeof(gid_t));
+            if (gidsetsize)
+                grouplist = alloca(gidsetsize * sizeof(gid_t));
             ret = get_errno(getgroups(gidsetsize, grouplist));
-            if (!is_error(ret)) {
+            if (gidsetsize && !is_error(ret)) {
                 target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize * 4, 0);
                 if (!target_grouplist) {
                     ret = -TARGET_EFAULT;