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Commit ac2a6599 authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
Browse files

uml: fix mm_context memory leak 



[ Spotted by Miklos ]

Fix a memory leak in init_new_context.  The struct page ** buffer allocated
for install_special_mapping was never recorded, and thus leaked when the
mm_struct was freed.  Fix it by saving the pointer in mm_context_t and freeing
it in arch_exit_mmap.

Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5aaf5f7b

arch/um/include/um_mmu.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
typedef struct mm_context {

	struct mm_id id;

	struct uml_ldt ldt;

	struct page **stub_pages;

} mm_context_t;



extern void __switch_mm(struct mm_id * mm_idp);

arch/um/kernel/skas/mmu.c

+5 −0
Original line number Diff line number Diff line
@@ -91,6 +91,8 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm) 
		goto out_free;

	}



	to_mm->stub_pages = NULL;



	return 0;



 out_free:
@@ -126,6 +128,7 @@ void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) 


	pages[0] = virt_to_page(&__syscall_stub_start);

	pages[1] = virt_to_page(mm->context.id.stack);

	mm->context.stub_pages = pages;



	/* dup_mmap already holds mmap_sem */

	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
@@ -147,6 +150,8 @@ void arch_exit_mmap(struct mm_struct *mm) 
{

	pte_t *pte;



	if (mm->context.stub_pages != NULL)

		kfree(mm->context.stub_pages);

	pte = virt_to_pte(mm, STUB_CODE);

	if (pte != NULL)

		pte_clear(mm, STUB_CODE, pte);