From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- net/ceph/msgpool.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 net/ceph/msgpool.c (limited to 'net/ceph/msgpool.c') diff --git a/net/ceph/msgpool.c b/net/ceph/msgpool.c new file mode 100644 index 000000000..e3ecb80cd --- /dev/null +++ b/net/ceph/msgpool.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +#include +#include +#include +#include + +#include +#include + +static void *msgpool_alloc(gfp_t gfp_mask, void *arg) +{ + struct ceph_msgpool *pool = arg; + struct ceph_msg *msg; + + msg = ceph_msg_new2(pool->type, pool->front_len, pool->max_data_items, + gfp_mask, true); + if (!msg) { + dout("msgpool_alloc %s failed\n", pool->name); + } else { + dout("msgpool_alloc %s %p\n", pool->name, msg); + msg->pool = pool; + } + return msg; +} + +static void msgpool_free(void *element, void *arg) +{ + struct ceph_msgpool *pool = arg; + struct ceph_msg *msg = element; + + dout("msgpool_release %s %p\n", pool->name, msg); + msg->pool = NULL; + ceph_msg_put(msg); +} + +int ceph_msgpool_init(struct ceph_msgpool *pool, int type, + int front_len, int max_data_items, int size, + const char *name) +{ + dout("msgpool %s init\n", name); + pool->type = type; + pool->front_len = front_len; + pool->max_data_items = max_data_items; + pool->pool = mempool_create(size, msgpool_alloc, msgpool_free, pool); + if (!pool->pool) + return -ENOMEM; + pool->name = name; + return 0; +} + +void ceph_msgpool_destroy(struct ceph_msgpool *pool) +{ + dout("msgpool %s destroy\n", pool->name); + mempool_destroy(pool->pool); +} + +struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len, + int max_data_items) +{ + struct ceph_msg *msg; + + if (front_len > pool->front_len || + max_data_items > pool->max_data_items) { + pr_warn_ratelimited("%s need %d/%d, pool %s has %d/%d\n", + __func__, front_len, max_data_items, pool->name, + pool->front_len, pool->max_data_items); + WARN_ON_ONCE(1); + + /* try to alloc a fresh message */ + return ceph_msg_new2(pool->type, front_len, max_data_items, + GFP_NOFS, false); + } + + msg = mempool_alloc(pool->pool, GFP_NOFS); + dout("msgpool_get %s %p\n", pool->name, msg); + return msg; +} + +void ceph_msgpool_put(struct ceph_msgpool *pool, struct ceph_msg *msg) +{ + dout("msgpool_put %s %p\n", pool->name, msg); + + /* reset msg front_len; user may have changed it */ + msg->front.iov_len = pool->front_len; + msg->hdr.front_len = cpu_to_le32(pool->front_len); + + msg->data_length = 0; + msg->num_data_items = 0; + + kref_init(&msg->kref); /* retake single ref */ + mempool_free(msg, pool->pool); +} -- cgit v1.3.1