Messages in this thread Patch in this message | | | From | Wupeng Ma <> | Subject | [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock | Date | Mon, 16 Jan 2023 19:58:10 +0800 |
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From: Ma Wupeng <mawupeng1@huawei.com>
While testing mlock, we have a problem if the len of mlock is ULONG_MAX. The return value of mlock is zero. But nothing will be locked since the len in do_mlock overflows to zero due to the following code in mlock:
len = PAGE_ALIGN(len + (offset_in_page(start)));
The same problem happens in munlock.
Add new check and return -EINVAL to fix this overflowing scenarios since they are absolutely wrong.
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com> --- mm/mlock.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/mm/mlock.c b/mm/mlock.c index 7032f6dd0ce1..5a4e767feb28 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -569,6 +569,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla unsigned long locked; unsigned long lock_limit; int error = -ENOMEM; + size_t old_len = len; start = untagged_addr(start); @@ -578,6 +579,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla len = PAGE_ALIGN(len + (offset_in_page(start))); start &= PAGE_MASK; + if (old_len != 0 && len == 0) + return -EINVAL; + lock_limit = rlimit(RLIMIT_MEMLOCK); lock_limit >>= PAGE_SHIFT; locked = len >> PAGE_SHIFT; @@ -632,12 +636,16 @@ SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) { int ret; + size_t old_len = len; start = untagged_addr(start); len = PAGE_ALIGN(len + (offset_in_page(start))); start &= PAGE_MASK; + if (old_len != 0 && len == 0) + return -EINVAL; + if (mmap_write_lock_killable(current->mm)) return -EINTR; ret = apply_vma_lock_flags(start, len, 0); -- 2.25.1
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