The patch titled
Subject: swapon: check validity of swap_flags
has been added to the -mm tree. Its filename is
swapon-check-validity-of-swap_flags.patch
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From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: swapon: check validity of swap_flags
Most system calls taking flags first check that the flags passed in are
valid, and that helps userspace to detect when new flags are supported.
But swapon never did so: start checking now, to help if we ever want to
support more swap_flags in future.
It's difficult to get stray bits set in an int, and swapon is not widely
used, so this is most unlikely to break any userspace; but we can just
revert if it turns out to do so.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 3 +++
mm/swapfile.c | 3 +++
2 files changed, 6 insertions(+)
diff -puN include/linux/swap.h~swapon-check-validity-of-swap_flags include/linux/swap.h
--- a/include/linux/swap.h~swapon-check-validity-of-swap_flags
+++ a/include/linux/swap.h
@@ -21,6 +21,9 @@ struct bio;
#define SWAP_FLAG_PRIO_SHIFT 0
#define SWAP_FLAG_DISCARD 0x10000 /* discard swap cluster after use */
+#define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
+ SWAP_FLAG_DISCARD)
+
static inline int current_is_kswapd(void)
{
return current->flags & PF_KSWAPD;
diff -puN mm/swapfile.c~swapon-check-validity-of-swap_flags mm/swapfile.c
--- a/mm/swapfile.c~swapon-check-validity-of-swap_flags
+++ a/mm/swapfile.c
@@ -2022,6 +2022,9 @@ SYSCALL_DEFINE2(swapon, const char __use
struct page *page = NULL;
struct inode *inode = NULL;
+ if (swap_flags & ~SWAP_FLAGS_VALID)
+ return -EINVAL;
+
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
_
Subject: Subject: swapon: check validity of swap_flags
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
origin.patch
mm-hugetlb-cleanup-duplicated-code-in-unmapping-vm-range.patch
linux-next.patch
mm-for-fs-add-truncate_pagecache_range.patch
mm-for-fs-add-truncate_pagecache_range-fix.patch
x86-stop-recursive-fault-in-print_context_stack-after-stack-overflow.patch
swapon-check-validity-of-swap_flags.patch
memcg-change-behavior-of-moving-charges-at-task-move.patch
memcg-swap-mem_cgroup_move_swap_account-never-needs-fixup.patch
memcg-swap-use-mem_cgroup_uncharge_swap.patch
radix-tree-introduce-bit-optimized-iterator.patch
radix-tree-introduce-bit-optimized-iterator-v3.patch
radix-tree-introduce-bit-optimized-iterator-v3-fix.patch
radix-tree-rewrite-gang-lookup-with-using-iterator.patch
radix-tree-use-iterators-in-find_get_pages-functions.patch
prio_tree-debugging-patch.patch
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