diff options
| author | Andy Lutomirski | 2019-07-11 20:57:43 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2019-07-12 11:05:45 -0700 |
| commit | b5d1c39f34d1c9bca0c4b9ae2e339fbbe264a9c7 (patch) | |
| tree | a3f85255181b5ad7416dc978c3c74bc88e6088a1 | |
| parent | aa712399c1e8245c375a5c44760de684ec2ebefb (diff) | |
mm/gup.c: remove some BUG_ONs from get_gate_page()
If we end up without a PGD or PUD entry backing the gate area, don't BUG
-- just fail gracefully.
It's not entirely implausible that this could happen some day on x86. It
doesn't right now even with an execute-only emulated vsyscall page because
the fixmap shares the PUD, but the core mm code shouldn't rely on that
particular detail to avoid OOPSing.
Link: http://lkml.kernel.org/r/a1d9f4efb75b9d464e59fd6af00104b21c58f6f7.1561610798.git.luto@kernel.org
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/gup.c | 9 |
1 files changed, 6 insertions, 3 deletions
@@ -586,11 +586,14 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address, pgd = pgd_offset_k(address); else pgd = pgd_offset_gate(mm, address); - BUG_ON(pgd_none(*pgd)); + if (pgd_none(*pgd)) + return -EFAULT; p4d = p4d_offset(pgd, address); - BUG_ON(p4d_none(*p4d)); + if (p4d_none(*p4d)) + return -EFAULT; pud = pud_offset(p4d, address); - BUG_ON(pud_none(*pud)); + if (pud_none(*pud)) + return -EFAULT; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) return -EFAULT; |