block/rnbd-clt: Fix sg table use after free

Since dynamically allocate sglist is used for rnbd_iu, we can't free sg table after send_usr_msg since the callback function (cqe.done) could still access the sglist. Otherwise KASAN reports UAF issue: [ 4856.600257] BUG: KASAN: use-after-free in dma_direct_unmap_sg+0x53/0x290 [ 4856.600772] Read of size 4 at addr ffff888206af3a98 by task swapper/1/0 [ 4856.601729] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G W 5.10.0-pserver #5.10.0-1+feature+linux+next+20201214.1025+0910d71 [ 4856.601748] Hardware name: Supermicro Super Server/X11DDW-L, BIOS 3.3 02/21/2020 [ 4856.601766] Call Trace: [ 4856.601785] <IRQ> [ 4856.601822] dump_stack+0x99/0xcb [ 4856.601856] ? dma_direct_unmap_sg+0x53/0x290 [ 4856.601888] print_address_description.constprop.7+0x1e/0x230 [ 4856.601913] ? freeze_kernel_threads+0x73/0x73 [ 4856.601965] ? mark_held_locks+0x29/0xa0 [ 4856.602019] ? dma_direct_unmap_sg+0x53/0x290 [ 4856.602039] ? dma_direct_unmap_sg+0x53/0x290 [ 4856.602079] kasan_report.cold.9+0x37/0x7c [ 4856.602188] ? mlx5_ib_post_recv+0x430/0x520 [mlx5_ib] [ 4856.602209] ? dma_direct_unmap_sg+0x53/0x290 [ 4856.602256] dma_direct_unmap_sg+0x53/0x290 [ 4856.602366] complete_rdma_req+0x188/0x4b0 [rtrs_client] [ 4856.602451] ? rtrs_clt_close+0x80/0x80 [rtrs_client] [ 4856.602535] ? mlx5_ib_poll_cq+0x48b/0x16e0 [mlx5_ib] [ 4856.602589] ? radix_tree_insert+0x3a0/0x3a0 [ 4856.602610] ? do_raw_spin_lock+0x119/0x1d0 [ 4856.602647] ? rwlock_bug.part.1+0x60/0x60 [ 4856.602740] rtrs_clt_rdma_done+0x3f7/0x670 [rtrs_client] [ 4856.602804] ? rtrs_clt_rdma_cm_handler+0xda0/0xda0 [rtrs_client] [ 4856.602857] ? check_flags.part.31+0x6c/0x1f0 [ 4856.602927] ? rcu_read_lock_sched_held+0xaf/0xe0 [ 4856.602963] ? rcu_read_lock_bh_held+0xc0/0xc0 [ 4856.603137] __ib_process_cq+0x10a/0x350 [ib_core] [ 4856.603309] ib_poll_handler+0x41/0x1c0 [ib_core] [ 4856.603358] irq_poll_softirq+0xe6/0x280 [ 4856.603392] ? lockdep_hardirqs_on_prepare+0x111/0x210 [ 4856.603446] __do_softirq+0x10d/0x646 [ 4856.603540] asm_call_irq_on_stack+0x12/0x20 [ 4856.603563] </IRQ> [ 4856.605096] Allocated by task 8914: [ 4856.605510] kasan_save_stack+0x19/0x40 [ 4856.605532] __kasan_kmalloc.constprop.7+0xc1/0xd0 [ 4856.605552] __kmalloc+0x155/0x320 [ 4856.605574] __sg_alloc_table+0x155/0x1c0 [ 4856.605594] sg_alloc_table+0x1f/0x50 [ 4856.605620] send_msg_sess_info+0x119/0x2e0 [rnbd_client] [ 4856.605646] remap_devs+0x71/0x210 [rnbd_client] [ 4856.605676] init_sess+0xad8/0xe10 [rtrs_client] [ 4856.605706] rtrs_clt_reconnect_work+0xd6/0x170 [rtrs_client] [ 4856.605728] process_one_work+0x521/0xa90 [ 4856.605748] worker_thread+0x65/0x5b0 [ 4856.605769] kthread+0x1f2/0x210 [ 4856.605789] ret_from_fork+0x22/0x30 [ 4856.606159] Freed by task 8914: [ 4856.606559] kasan_save_stack+0x19/0x40 [ 4856.606580] kasan_set_track+0x1c/0x30 [ 4856.606601] kasan_set_free_info+0x1b/0x30 [ 4856.606622] __kasan_slab_free+0x108/0x150 [ 4856.606642] slab_free_freelist_hook+0x64/0x190 [ 4856.606661] kfree+0xe2/0x650 [ 4856.606681] __sg_free_table+0xa4/0x100 [ 4856.606707] send_msg_sess_info+0x1d6/0x2e0 [rnbd_client] [ 4856.606733] remap_devs+0x71/0x210 [rnbd_client] [ 4856.606763] init_sess+0xad8/0xe10 [rtrs_client] [ 4856.606792] rtrs_clt_reconnect_work+0xd6/0x170 [rtrs_client] [ 4856.606813] process_one_work+0x521/0xa90 [ 4856.606833] worker_thread+0x65/0x5b0 [ 4856.606853] kthread+0x1f2/0x210 [ 4856.606872] ret_from_fork+0x22/0x30 The solution is to free iu's sgtable after the iu is not used anymore. And also move sg_alloc_table into rnbd_get_iu accordingly. Fixes: 5a1328d ("block/rnbd-clt: Dynamically allocate sglist for rnbd_iu") Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com> Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
dabrace · Jan 8, 2021 · 80f9909 · 80f9909
1 parent 1a84e7c
commit 80f9909
Showing 1 changed file with 7 additions and 8 deletions.
diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
@@ -375,12 +375,19 @@ static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
 	init_waitqueue_head(&iu->comp.wait);
 	iu->comp.errno = INT_MAX;
 
+	if (sg_alloc_table(&iu->sgt, 1, GFP_KERNEL)) {
+		rnbd_put_permit(sess, permit);
+		kfree(iu);
+		return NULL;
+	}
+
 	return iu;
 }
 
 static void rnbd_put_iu(struct rnbd_clt_session *sess, struct rnbd_iu *iu)
 {
 	if (atomic_dec_and_test(&iu->refcount)) {
+		sg_free_table(&iu->sgt);
 		rnbd_put_permit(sess, iu->permit);
 		kfree(iu);
 	}
@@ -487,8 +494,6 @@ static int send_msg_close(struct rnbd_clt_dev *dev, u32 device_id, bool wait)
 	iu->buf = NULL;
 	iu->dev = dev;
 
-	sg_alloc_table(&iu->sgt, 1, GFP_KERNEL);
-
 	msg.hdr.type	= cpu_to_le16(RNBD_MSG_CLOSE);
 	msg.device_id	= cpu_to_le32(device_id);
 
@@ -502,7 +507,6 @@ static int send_msg_close(struct rnbd_clt_dev *dev, u32 device_id, bool wait)
 		err = errno;
 	}
 
-	sg_free_table(&iu->sgt);
 	rnbd_put_iu(sess, iu);
 	return err;
 }
@@ -575,7 +579,6 @@ static int send_msg_open(struct rnbd_clt_dev *dev, bool wait)
 	iu->buf = rsp;
 	iu->dev = dev;
 
-	sg_alloc_table(&iu->sgt, 1, GFP_KERNEL);
 	sg_init_one(iu->sgt.sgl, rsp, sizeof(*rsp));
 
 	msg.hdr.type	= cpu_to_le16(RNBD_MSG_OPEN);
@@ -594,7 +597,6 @@ static int send_msg_open(struct rnbd_clt_dev *dev, bool wait)
 		err = errno;
 	}
 
-	sg_free_table(&iu->sgt);
 	rnbd_put_iu(sess, iu);
 	return err;
 }
@@ -622,8 +624,6 @@ static int send_msg_sess_info(struct rnbd_clt_session *sess, bool wait)
 
 	iu->buf = rsp;
 	iu->sess = sess;
-
-	sg_alloc_table(&iu->sgt, 1, GFP_KERNEL);
 	sg_init_one(iu->sgt.sgl, rsp, sizeof(*rsp));
 
 	msg.hdr.type = cpu_to_le16(RNBD_MSG_SESS_INFO);
@@ -650,7 +650,6 @@ static int send_msg_sess_info(struct rnbd_clt_session *sess, bool wait)
 	} else {
 		err = errno;
 	}
-	sg_free_table(&iu->sgt);
 	rnbd_put_iu(sess, iu);
 	return err;
 }