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mm/pagemap: add mmap_assert_locked() annotations to find_vma*()

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find_vma() and variants need protection when used.  This patch adds
mmap_assert_lock() calls in the functions.

To make sure the invariant is satisfied, we also need to add a
mmap_read_lock() around the get_user_pages_remote() call in
get_arg_page().  The lock is not strictly necessary because the mm has
been newly created, but the extra cost is limited because the same mutex
was also acquired shortly before in __bprm_mm_init(), so it is hot and
uncontended.

[penguin-kernel@i-love.sakura.ne.jp: TOMOYO needs the same protection which get_arg_page() needs]
  Link: https://lkml.kernel.org/r/58bb6bf7-a57e-8a40-e74b-39584b415152@i-love.sakura.ne.jp

Link: https://lkml.kernel.org/r/20210731175341.3458608-1-lrizzo@google.com
Signed-off-by: Luigi Rizzo <lrizzo@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Luigi Rizzo 2021-09-02 14:56:46 -07:00 committed by Linus Torvalds
parent e15710bf04
commit 5b78ed24e8
3 changed files with 13 additions and 4 deletions
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2
fs/exec.c
View File

@ -217,8 +217,10 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
* We are doing an exec(). 'current' is the process
* doing the exec and bprm->mm is the new process's mm.
*/
mmap_read_lock(bprm->mm);
ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
&page, NULL, NULL);
mmap_read_unlock(bprm->mm);
if (ret <= 0)
return NULL;

2
mm/mmap.c
View File

@ -534,6 +534,7 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr,
{
struct rb_node **__rb_link, *__rb_parent, *rb_prev;
mmap_assert_locked(mm);
__rb_link = &mm->mm_rb.rb_node;
rb_prev = __rb_parent = NULL;
@ -2303,6 +2304,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
struct rb_node *rb_node;
struct vm_area_struct *vma;
mmap_assert_locked(mm);
/* Check the cache first. */
vma = vmacache_find(mm, addr);
if (likely(vma))

13
security/tomoyo/domain.c
View File

@ -897,6 +897,9 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
struct tomoyo_page_dump *dump)
{
struct page *page;
#ifdef CONFIG_MMU
int ret;
#endif
/* dump->data is released by tomoyo_find_next_domain(). */
if (!dump->data) {
@ -909,11 +912,13 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
/*
* This is called at execve() time in order to dig around
* in the argv/environment of the new proceess
* (represented by bprm). 'current' is the process doing
* the execve().
* (represented by bprm).
*/
if (get_user_pages_remote(bprm->mm, pos, 1,
FOLL_FORCE, &page, NULL, NULL) <= 0)
mmap_read_lock(bprm->mm);
ret = get_user_pages_remote(bprm->mm, pos, 1,
FOLL_FORCE, &page, NULL, NULL);
mmap_read_unlock(bprm->mm);
if (ret <= 0)
return false;
#else
page = bprm->page[pos / PAGE_SIZE];