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authorTomas Bortoli <tomasbortoli@gmail.com>2018-08-14 20:43:42 +0300
committerDominique Martinet <dominique.martinet@cea.fr>2018-09-07 19:39:47 +0300
commit728356dedeff8ef999cb436c71333ef4ac51a81c (patch)
treeca05afe6f54f9f2bec2128f4cfd97cfc6ff23764 /net/9p/trans_virtio.c
parent43cbcbee9938b17f77cf34f1bc12d302f456810f (diff)
downloadlinux-728356dedeff8ef999cb436c71333ef4ac51a81c.tar.xz
9p: Add refcount to p9_req_t
To avoid use-after-free(s), use a refcount to keep track of the usable references to any instantiated struct p9_req_t. This commit adds p9_req_put(), p9_req_get() and p9_req_try_get() as wrappers to kref_put(), kref_get() and kref_get_unless_zero(). These are used by the client and the transports to keep track of valid requests' references. p9_free_req() is added back and used as callback by kref_put(). Add SLAB_TYPESAFE_BY_RCU as it ensures that the memory freed by kmem_cache_free() will not be reused for another type until the rcu synchronisation period is over, so an address gotten under rcu read lock is safe to inc_ref() without corrupting random memory while the lock is held. Link: http://lkml.kernel.org/r/1535626341-20693-1-git-send-email-asmadeus@codewreck.org Co-developed-by: Dominique Martinet <dominique.martinet@cea.fr> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> Reported-by: syzbot+467050c1ce275af2a5b8@syzkaller.appspotmail.com Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Diffstat (limited to 'net/9p/trans_virtio.c')
-rw-r--r--net/9p/trans_virtio.c26
1 files changed, 22 insertions, 4 deletions
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 3dd6ce1c0f2d..eb596c2ed546 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -207,6 +207,13 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
return 1;
}
+/* Reply won't come, so drop req ref */
+static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req)
+{
+ p9_req_put(req);
+ return 0;
+}
+
/**
* pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
* this takes a list of pages.
@@ -404,6 +411,7 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
struct scatterlist *sgs[4];
size_t offs;
int need_drop = 0;
+ int kicked = 0;
p9_debug(P9_DEBUG_TRANS, "virtio request\n");
@@ -411,8 +419,10 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
__le32 sz;
int n = p9_get_mapped_pages(chan, &out_pages, uodata,
outlen, &offs, &need_drop);
- if (n < 0)
- return n;
+ if (n < 0) {
+ err = n;
+ goto err_out;
+ }
out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
if (n != outlen) {
__le32 v = cpu_to_le32(n);
@@ -428,8 +438,10 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
} else if (uidata) {
int n = p9_get_mapped_pages(chan, &in_pages, uidata,
inlen, &offs, &need_drop);
- if (n < 0)
- return n;
+ if (n < 0) {
+ err = n;
+ goto err_out;
+ }
in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
if (n != inlen) {
__le32 v = cpu_to_le32(n);
@@ -498,6 +510,7 @@ req_retry_pinned:
}
virtqueue_kick(chan->vq);
spin_unlock_irqrestore(&chan->lock, flags);
+ kicked = 1;
p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD);
/*
@@ -518,6 +531,10 @@ err_out:
}
kvfree(in_pages);
kvfree(out_pages);
+ if (!kicked) {
+ /* reply won't come */
+ p9_req_put(req);
+ }
return err;
}
@@ -750,6 +767,7 @@ static struct p9_trans_module p9_virtio_trans = {
.request = p9_virtio_request,
.zc_request = p9_virtio_zc_request,
.cancel = p9_virtio_cancel,
+ .cancelled = p9_virtio_cancelled,
/*
* We leave one entry for input and one entry for response
* headers. We also skip one more entry to accomodate, address