uml: fix mm_context memory leak (ac2a6599) · Commits · 戴 / test

[ 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:

Jeff Dike <jdike@linux.intel.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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);

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