mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-07 03:18:31 +00:00
mm/gup.c: remove some BUG_ONs from get_gate_page()
[ Upstream commit b5d1c39f34
]
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>
This commit is contained in:
parent
fa099d6ddf
commit
041b127df7
1 changed files with 6 additions and 3 deletions
9
mm/gup.c
9
mm/gup.c
|
@ -458,11 +458,14 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
|
||||||
pgd = pgd_offset_k(address);
|
pgd = pgd_offset_k(address);
|
||||||
else
|
else
|
||||||
pgd = pgd_offset_gate(mm, address);
|
pgd = pgd_offset_gate(mm, address);
|
||||||
BUG_ON(pgd_none(*pgd));
|
if (pgd_none(*pgd))
|
||||||
|
return -EFAULT;
|
||||||
p4d = p4d_offset(pgd, address);
|
p4d = p4d_offset(pgd, address);
|
||||||
BUG_ON(p4d_none(*p4d));
|
if (p4d_none(*p4d))
|
||||||
|
return -EFAULT;
|
||||||
pud = pud_offset(p4d, address);
|
pud = pud_offset(p4d, address);
|
||||||
BUG_ON(pud_none(*pud));
|
if (pud_none(*pud))
|
||||||
|
return -EFAULT;
|
||||||
pmd = pmd_offset(pud, address);
|
pmd = pmd_offset(pud, address);
|
||||||
if (!pmd_present(*pmd))
|
if (!pmd_present(*pmd))
|
||||||
return -EFAULT;
|
return -EFAULT;
|
||||||
|
|
Loading…
Reference in a new issue