diff options
| author | Doug Ledford <dledford@redhat.com> | 2012-05-31 16:26:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-31 17:49:31 -0700 |
| commit | 2c12ea498f349207c28840c0ed9654321aab7720 (patch) | |
| tree | ef0f938e66a8a8b038e5c6be29e7f27294023c7e | |
| parent | d6629859b36d953a4b1369b749f178736911bf10 (diff) | |
ipc/mqueue: correct mq_attr_ok test
While working on the other parts of the mqueue stuff, I noticed that the
calculation for overflow in mq_attr_ok didn't actually match reality (this
is especially true since my last patch which changed how we account memory
slightly).
In particular, we used to test for overflow using:
msgs * msgsize + msgs * sizeof(struct msg_msg *)
That was never really correct because each message we allocate via
load_msg() is actually a struct msg_msg followed by the data for the
message (and if struct msg_msg + data exceeds PAGE_SIZE we end up
allocating struct msg_msgseg structs too, but accounting for them would
get really tedious, so let's ignore those...they're only a pointer in size
anyway). This patch updates the calculation to be more accurate in
regards to maximum possible memory consumption by the mqueue.
[akpm@linux-foundation.org: add a local to simplify overflow-checking expression]
Signed-off-by: Doug Ledford <dledford@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Manfred Spraul <manfred@colorfullife.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | ipc/mqueue.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 3c72a05dc32..076399ce363 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -676,6 +676,9 @@ static void remove_notification(struct mqueue_inode_info *info) static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) { + int mq_treesize; + unsigned long total_size; + if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) return 0; if (capable(CAP_SYS_RESOURCE)) { @@ -690,9 +693,11 @@ static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) /* check for overflow */ if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) return 0; - if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize - + sizeof (struct msg_msg *))) < - (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) + mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) + + min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) * + sizeof(struct posix_msg_tree_node); + total_size = attr->mq_maxmsg * attr->mq_msgsize; + if (total_size + mq_treesize < total_size) return 0; return 1; } |