[Qemu-devel] [BUG][PATCH] execve processesing NULL args

[Qemu-devel] [BUG][PATCH] execve processesing NULL args

[Thayne Harbaugh]

[-- Attachment #1: Type: text/plain, Size: 98 bytes --]

Here's a patch to avoid processing NULL args in execve.  It prevents
trying to dereference NULL.


[-- Attachment #2: 50_execve_null_args.patch --]
[-- Type: text/x-patch, Size: 2178 bytes --]

Index: qemu/linux-user/syscall.c
===================================================================
--- qemu.orig/linux-user/syscall.c	2007-11-19 20:45:20.000000000 -0700
+++ qemu/linux-user/syscall.c	2007-11-19 20:48:54.000000000 -0700
@@ -3515,7 +3515,7 @@
 
             argc = 0;
             guest_argp = arg2;
-            for (gp = guest_argp; ; gp += sizeof(abi_ulong)) {
+            for (gp = guest_argp; gp; gp += sizeof(abi_ulong)) {
                 if (get_user_ual(addr, gp))
                     goto efault;
                 if (!addr)
@@ -3524,7 +3524,7 @@
             }
             envc = 0;
             guest_envp = arg3;
-            for (gp = guest_envp; ; gp += sizeof(abi_ulong)) {
+            for (gp = guest_envp; gp; gp += sizeof(abi_ulong)) {
                 if (get_user_ual(addr, gp))
                     goto efault;
                 if (!addr)
@@ -3535,7 +3535,7 @@
             argp = alloca((argc + 1) * sizeof(void *));
             envp = alloca((envc + 1) * sizeof(void *));
 
-            for (gp = guest_argp, q = argp; ;
+            for (gp = guest_argp, q = argp; gp;
                   gp += sizeof(abi_ulong), q++) {
                 if (get_user_ual(addr, gp))
                     goto execve_efault;
@@ -3546,7 +3546,7 @@
             }
             *q = NULL;
 
-            for (gp = guest_envp, q = envp; ;
+            for (gp = guest_envp, q = envp; gp;
                   gp += sizeof(abi_ulong), q++) {
                 if (get_user_ual(addr, gp))
                     goto execve_efault;
@@ -3568,14 +3568,14 @@
             ret = -TARGET_EFAULT;
 
         execve_end:
-            for (gp = guest_argp, q = argp; *q;
+            for (gp = guest_argp, q = argp; gp && *q;
                   gp += sizeof(abi_ulong), q++) {
                 if (get_user_ual(addr, gp)
                     || !addr)
                     break;
                 unlock_user(*q, addr, 0);
             }
-            for (gp = guest_envp, q = envp; *q;
+            for (gp = guest_envp, q = envp; gp && *q;
                   gp += sizeof(abi_ulong), q++) {
                 if (get_user_ual(addr, gp)
                     || !addr)