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SubjectRe: [PATCH] error path in setup_arg_pages() misses vm_unacct_memory()
>>Kirill Korotaev <dev@sw.ru> wrote:
>>
>>> This patch fixes error path in setup_arg_pages() functions, since it
>>> misses vm_unacct_memory() after successful call of
>>> security_vm_enough_memory(). Also it cleans up error path.
>>
>>Ugh. The identifier `security_vm_enough_memory()' sounds like some
>>predicate which has no side-effects. Except it performs accounting. Hence
>>bugs like this.
>>
>>It's a shame that you mixed a largeish cleanup along with a bugfix - please
>>don't do that in future.
>>
>>Patch looks OK to me. Hugh, could you please double-check sometime?
>
>
> It's a good find, and the patch looks correct to me, so far as it goes.
> But I think it's the wrong patch, and incomplete: it can be done more
> appropriately, more simply and more completely in insert_vm_struct itself.
> I'll post a replacement patch (or admit I'm wrong) in a little while.

this looks like the weirdest solution to me...
also it looks like not all the callers of insert_vm_struct do call
security_vm_enough_memory(), e.g. ./arch/sparc/mm/sun4c.c

------------------------------------------------------------------

Also, Pavel missed ppc64 version of setup_arg_pages due to different
name. I attached 2 new additional patches:



1. diff-ms-ppsleak-20050913:

[PATCH] error path in ppc64::arch_setup_additional_pages() misses
vm_unacct_memory() and kmem_cache_free()

This patch fixes error path in arch_setup_additional_pages() function,
since it misses vm_unacct_memory() and kmmem_cache_free() after
successful call of security_vm_enough_memory().

Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@sw.ru>



2. diff-ms-ppscleanup-20050913:
[PATCH] This patch cleanups error path in
ppc64::arch_setup_additional_pages() function.

Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@sw.ru>



Kirill
--- linux-2.6.13.1/arch/ppc64/kernel/vdso.c.ppcfix 2005-09-13 15:44:17.000000000 +0400
+++ linux-2.6.13.1/arch/ppc64/kernel/vdso.c 2005-09-13 15:47:26.000000000 +0400
@@ -237,8 +237,11 @@ int arch_setup_additional_pages(struct l
*/
vdso_base = get_unmapped_area(NULL, vdso_base,
vdso_pages << PAGE_SHIFT, 0, 0);
- if (vdso_base & ~PAGE_MASK)
+ if (vdso_base & ~PAGE_MASK) {
+ vm_unacct_memory(vdso_pages);
+ kmem_cache_free(vm_area_cachep, vma);
return (int)vdso_base;
+ }

current->thread.vdso_base = vdso_base;
--- linux-2.6.13.1/arch/ppc64/kernel/vdso.c.ppccln 2005-09-13 15:47:26.000000000 +0400
+++ linux-2.6.13.1/arch/ppc64/kernel/vdso.c 2005-09-13 15:55:08.000000000 +0400
@@ -221,13 +221,13 @@ int arch_setup_additional_pages(struct l
if (vdso_pages == 0)
return 0;

+ vdso_base = -ENOMEM;
vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (vma == NULL)
- return -ENOMEM;
- if (security_vm_enough_memory(vdso_pages)) {
- kmem_cache_free(vm_area_cachep, vma);
- return -ENOMEM;
- }
+ goto out;
+ if (security_vm_enough_memory(vdso_pages))
+ goto out_free;
+
memset(vma, 0, sizeof(*vma));

/*
@@ -237,11 +237,8 @@ int arch_setup_additional_pages(struct l
*/
vdso_base = get_unmapped_area(NULL, vdso_base,
vdso_pages << PAGE_SHIFT, 0, 0);
- if (vdso_base & ~PAGE_MASK) {
- vm_unacct_memory(vdso_pages);
- kmem_cache_free(vm_area_cachep, vma);
- return (int)vdso_base;
- }
+ if (vdso_base & ~PAGE_MASK)
+ goto out_unacct;

current->thread.vdso_base = vdso_base;

@@ -274,6 +271,13 @@ int arch_setup_additional_pages(struct l
up_write(&mm->mmap_sem);

return 0;
+
+out_unacct:
+ vm_unacct_memory(vdso_pages);
+out_free:
+ kmem_cache_free(vm_area_cachep, vma);
+out:
+ return (int)vdso_base;
}

static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
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