Re: [Announce] Strace Test

[Andrew Morton]

Nikita Danilov <Nikita@xxxxxxxxxxx> wrote:
>
>  > Strace Test uses a modified version of strace 4.5.1.  
>   > Instead of printing out information about system calls, 
>   > the modified version calls the syscalls with improper 
>   > values.
> 
>  It immediately DoSes kernel by calling sys_sysctl() with huge nlen:
>  printk() consumes all CPU.

Something like this?

--- 25/kernel/sysctl.c~sysctl-nlen-check	2004-02-19 02:36:20.000000000 -0800
+++ 25-akpm/kernel/sysctl.c	2004-02-19 02:37:40.000000000 -0800
@@ -913,6 +913,9 @@ asmlinkage long sys_sysctl(struct __sysc
 
 	if (copy_from_user(&tmp, args, sizeof(tmp)))
 		return -EFAULT;
+
+	if (tmp.nlen < 0 || tmp.nlen > CTL_MAXNAME)
+		return -EINVAL;
 	
 	if (tmp.nlen != 2 || copy_from_user(name, tmp.name, sizeof(name)) ||
 	    name[0] != CTL_KERN || name[1] != KERN_VERSION) { 

_

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