path: root/mm/swapfile.c
diff options
authorHugh Dickins <hughd@google.com>2012-03-28 14:42:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-28 17:14:35 -0700
commitd15cab975459fb6092eeba1be72c13621337784f (patch)
tree5c1d8d18c65a34eb738c97d75f2c44becdff1de3 /mm/swapfile.c
parent29fd66d289f2981e11c550f8b411a6d3d38be0cf (diff)
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@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index dae42f380d6..fafc26d1b1d 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2022,6 +2022,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
struct page *page = NULL;
struct inode *inode = NULL;
+ if (swap_flags & ~SWAP_FLAGS_VALID)
+ return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;