erofs: fix use-after-free of on-stack io[]

The root cause is the race as follows:
Thread #1                              Thread #2(irq ctx)

z_erofs_runqueue()
  struct z_erofs_decompressqueue io_A[];
  submit bio A
  z_erofs_decompress_kickoff(,,1)
                                       z_erofs_decompressqueue_endio(bio A)
                                       z_erofs_decompress_kickoff(,,-1)
                                       spin_lock_irqsave()
                                       atomic_add_return()
  io_wait_event()	-> pending_bios is already 0
  [end of function]
                                       wake_up_locked(io_A[]) // crash

Referenced backtrace in kernel 5.4:

[   10.129422] Unable to handle kernel paging request at virtual address eb0454a4
[   10.364157] CPU: 0 PID: 709 Comm: getprop Tainted: G        WC O      5.4.147-ab09225 #1
[   11.556325] [<c01b33b8>] (__wake_up_common) from [<c01b3300>] (__wake_up_locked+0x40/0x48)
[   11.565487] [<c01b3300>] (__wake_up_locked) from [<c044c8d0>] (z_erofs_vle_unzip_kickoff+0x6c/0xc0)
[   11.575438] [<c044c8d0>] (z_erofs_vle_unzip_kickoff) from [<c044c854>] (z_erofs_vle_read_endio+0x16c/0x17c)
[   11.586082] [<c044c854>] (z_erofs_vle_read_endio) from [<c06a80e8>] (clone_endio+0xb4/0x1d0)
[   11.595428] [<c06a80e8>] (clone_endio) from [<c04a1280>] (blk_update_request+0x150/0x4dc)
[   11.604516] [<c04a1280>] (blk_update_request) from [<c06dea28>] (mmc_blk_cqe_complete_rq+0x144/0x15c)
[   11.614640] [<c06dea28>] (mmc_blk_cqe_complete_rq) from [<c04a5d90>] (blk_done_softirq+0xb0/0xcc)
[   11.624419] [<c04a5d90>] (blk_done_softirq) from [<c010242c>] (__do_softirq+0x184/0x56c)
[   11.633419] [<c010242c>] (__do_softirq) from [<c01051e8>] (irq_exit+0xd4/0x138)
[   11.641640] [<c01051e8>] (irq_exit) from [<c010c314>] (__handle_domain_irq+0x94/0xd0)
[   11.650381] [<c010c314>] (__handle_domain_irq) from [<c04fde70>] (gic_handle_irq+0x50/0xd4)
[   11.659641] [<c04fde70>] (gic_handle_irq) from [<c0101b70>] (__irq_svc+0x70/0xb0)

Signed-off-by: Hongyu Jin <hongyu.jin@unisoc.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20220401115527.4935-1-hongyu.jin.cn@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 0ed880f42525b11b28ed93cd8dd38ceee464e373..e6dea6dfca161398c9e38324fc605e3a757ddd0f 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1066,12 +1066,9 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 
        /* wake up the caller thread for sync decompression */
        if (sync) {
-               unsigned long flags;
-
-               spin_lock_irqsave(&io->u.wait.lock, flags);
                if (!atomic_add_return(bios, &io->pending_bios))
-                       wake_up_locked(&io->u.wait);
-               spin_unlock_irqrestore(&io->u.wait.lock, flags);
+                       complete(&io->u.done);
+
                return;
        }
 
@@ -1217,7 +1214,7 @@ jobqueue_init(struct super_block *sb,
        } else {
 fg_out:
                q = fgq;
-               init_waitqueue_head(&fgq->u.wait);
+               init_completion(&fgq->u.done);
                atomic_set(&fgq->pending_bios, 0);
        }
        q->sb = sb;
@@ -1419,8 +1416,7 @@ static void z_erofs_runqueue(struct super_block *sb,
                return;
 
        /* wait until all bios are completed */
-       io_wait_event(io[JQ_SUBMIT].u.wait,
-                     !atomic_read(&io[JQ_SUBMIT].pending_bios));
+       wait_for_completion_io(&io[JQ_SUBMIT].u.done);
 
        /* handle synchronous decompress queue in the caller context */
        z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);

diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
index e043216b545f19ecb4b2d250b1e1efb2ca720823..800b11c53f5749ebcd3634a736b242b9fe887e9a 100644 (file)
--- a/fs/erofs/zdata.h
+++ b/fs/erofs/zdata.h
@@ -97,7 +97,7 @@ struct z_erofs_decompressqueue {
        z_erofs_next_pcluster_t head;
 
        union {
-               wait_queue_head_t wait;
+               struct completion done;
                struct work_struct work;
        } u;
 };