From 5b78ed24e8ec48602c1d6f5a188e58d000c81e2b Mon Sep 17 00:00:00 2001 From: Luigi Rizzo Date: Thu, 2 Sep 2021 14:56:46 -0700 Subject: mm/pagemap: add mmap_assert_locked() annotations to find_vma*() 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 Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs') diff --git a/fs/exec.c b/fs/exec.c index 41a888d4edde..fd292e9da4f9 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -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; -- cgit v1.2.3