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| author | Andy Lutomirski | 2019-07-12 05:57:43 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2019-07-31 07:27:08 +0200 |
| commit | 041b127df733ec1457dc60de41c091c5e73e3741 (patch) | |
| tree | 630fc460fefbea165e0f57ad233ee252653f63aa /mm | |
| parent | mm/gup.c: mark undo_dev_pagemap as __maybe_unused (diff) | |
| download | kernel-qcow2-linux-041b127df733ec1457dc60de41c091c5e73e3741.tar.gz kernel-qcow2-linux-041b127df733ec1457dc60de41c091c5e73e3741.tar.xz kernel-qcow2-linux-041b127df733ec1457dc60de41c091c5e73e3741.zip | |
mm/gup.c: remove some BUG_ONs from get_gate_page()
[ Upstream commit b5d1c39f34d1c9bca0c4b9ae2e339fbbe264a9c7 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/gup.c | 9 |
1 files changed, 6 insertions, 3 deletions
@@ -458,11 +458,14 @@ 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; |