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Don't zero out buffer in sched_getaffinity

PATCH In review Mike McCormack 2 participants 2 messages Apr 18, 2011

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Mike McCormack

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#0 lore raw

PATCH 1/1 Don't zero out buffer in sched_getaffinity

The kernel doesn't fill the buffer provided to sched_getaffinity with zero bytes, so neither should QEMU.

Depends on sched_getaffinity buffer overrun fix, but submitted separately to make rollback easier.

---
 linux-user/syscall.c |   13 +------------
 1 files changed, 1 insertions(+), 12 deletions(-)
linux-user/syscall.c +1 -12
index 19209a2..e2a5fd9 100644
@@ -6382,20 +6382,9 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
             ret = get_errno(sys_sched_getaffinity(arg1, mask_size, mask));
 
             if (!is_error(ret)) {
-                if (arg2 > ret) {
-                    /* Zero out any extra space kernel didn't fill */
-                    unsigned long zero = arg2 - ret;
-                    p = alloca(zero);
-                    memset(p, 0, zero);
-                    if (copy_to_user(arg3 + ret, p, zero)) {
-                        goto efault;
-                    }
-                    arg2 = ret;
-                }
-                if (copy_to_user(arg3, mask, arg2)) {
+                if (copy_to_user(arg3, mask, ret)) {
                     goto efault;
                 }
-                ret = arg2;
             }
         }
         break;
Signature · 1 line
1.7.0.4
Reviewed-by on v1 1/1
#1 lore raw
Quoted 9 lines · Mike McCormack

The kernel doesn't fill the buffer provided to sched_getaffinity with zero bytes, so neither should QEMU.

Depends on sched_getaffinity buffer overrun fix, but submitted separately to make rollback easier.

---
 linux-user/syscall.c |   13 +------------

 1 files changed, 1 insertions(+), 12 deletions(-)
Reviewed-by Stefan Hajnoczi <[email protected]>