Re: [PATCH] kernel/fork.c: VM accounting bugfix (2.6.11-rc3-bk5)

[Chris Wright]

Hi Mark,

* Mark F. Haigh (Mark.Haigh@xxxxxxxxxxxxxx) wrote:
> [Aargh!  Missing Signed-off-by.]
> 
> Unless I'm missing something, in kernel/fork.c, dup_mmap():
> 
> 			if (security_vm_enough_memory(len))
> 				goto fail_nomem;
> /* ... */
> fail_nomem:
> 	retval = -ENOMEM;
> 	vm_unacct_memory(charge);
> /* ... */
> 
> If security_vm_enough_memory() fails there, then we vm_unacct_memory()
> that we never accounted (if security_vm_enough_memory() fails, no memory
> is accounted).

You missed one subtle point.  That failure case actually unaccts 0 pages
(note the use of charge).  Not the nicest, but I believe correct.

thanks,
-chris
-- 
Linux Security Modules     http://lsm.immunix.org     http://lsm.bkbits.net
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