From 124f75f864f38327e3e7e182e6b6da5105e2bade Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 13 Feb 2022 22:42:30 -0500 Subject: [PATCH] clean overflow checks in count_mounts() a bit Wraparound checks in there are redundant (x + y < x and x + y < y are equivalent when x and y are both unsigned int). IMO more straightforward code would be better here... Signed-off-by: Al Viro --- fs/namespace.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 13d025a9ecf5..42d4fc21263b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2069,22 +2069,23 @@ static int invent_group_ids(struct mount *mnt, bool recurse) int count_mounts(struct mnt_namespace *ns, struct mount *mnt) { unsigned int max = READ_ONCE(sysctl_mount_max); - unsigned int mounts = 0, old, pending, sum; + unsigned int mounts = 0; struct mount *p; + if (ns->mounts >= max) + return -ENOSPC; + max -= ns->mounts; + if (ns->pending_mounts >= max) + return -ENOSPC; + max -= ns->pending_mounts; + for (p = mnt; p; p = next_mnt(p, mnt)) mounts++; - old = ns->mounts; - pending = ns->pending_mounts; - sum = old + pending; - if ((old > sum) || - (pending > sum) || - (max < sum) || - (mounts > (max - sum))) + if (mounts > max) return -ENOSPC; - ns->pending_mounts = pending + mounts; + ns->pending_mounts += mounts; return 0; }