From 4ca3b3df6d52aff8b42271a23d7f2218672cfbf8 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Fri, 17 Aug 2018 15:46:57 -0700 Subject: mm/fadvise.c: fix signed overflow UBSAN complaint [ Upstream commit a718e28f538441a3b6612da9ff226973376cdf0f ] Signed integer overflow is undefined according to the C standard. The overflow in ksys_fadvise64_64() is deliberate, but since it is signed overflow, UBSAN complains: UBSAN: Undefined behaviour in mm/fadvise.c:76:10 signed integer overflow: 4 + 9223372036854775805 cannot be represented in type 'long long int' Use unsigned types to do math. Unsigned overflow is defined so UBSAN will not complain about it. This patch doesn't change generated code. [akpm@linux-foundation.org: add comment explaining the casts] Link: http://lkml.kernel.org/r/20180629184453.7614-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin Reported-by: Reviewed-by: Andrew Morton Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- mm/fadvise.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/fadvise.c b/mm/fadvise.c index b8a5bc66b0c0..001877e32f0c 100644 --- a/mm/fadvise.c +++ b/mm/fadvise.c @@ -68,8 +68,12 @@ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) goto out; } - /* Careful about overflows. Len == 0 means "as much as possible" */ - endbyte = offset + len; + /* + * Careful about overflows. Len == 0 means "as much as possible". Use + * unsigned math because signed overflows are undefined and UBSan + * complains. + */ + endbyte = (u64)offset + (u64)len; if (!len || endbyte < len) endbyte = -1; else -- cgit v1.2.3 From e72977e87482759dba7181e0ec210c2db00c6124 Mon Sep 17 00:00:00 2001 From: Chas Williams Date: Thu, 6 Sep 2018 11:11:27 -0400 Subject: Fixes: Commit cdbf92675fad ("mm: numa: avoid waiting on freed migrated pages") Commit cdbf92675fad ("mm: numa: avoid waiting on freed migrated pages") was an incomplete backport of the upstream commit. It is necessary to always reset page_nid before attempting any early exit. The original commit conflicted due to lack of commit 82b0f8c39a38 ("mm: join struct fault_env and vm_fault") in 4.9 so it wasn't a clean application, and the change must have just gotten lost in the noise. Signed-off-by: Chas Williams Signed-off-by: Greg Kroah-Hartman --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 0127b788272f..c4ea57ee2fd1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1393,12 +1393,12 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, /* Migration could have started since the pmd_trans_migrating check */ if (!page_locked) { + page_nid = -1; if (!get_page_unless_zero(page)) goto out_unlock; spin_unlock(ptl); wait_on_page_locked(page); put_page(page); - page_nid = -1; goto out; } -- cgit v1.2.3