[PULL,09/27] block: Fix locking in media change monitor commands

Commit Message

Kevin Wolf Oct. 31, 2023, 6:59 p.m. UTC

blk_insert_bs() requires that the caller holds the AioContext lock for
the node to be inserted. Since commit c066e808e11, neglecting to do so
causes a crash when the child has to be moved to a different AioContext
to attach it to the BlockBackend.

This fixes qmp_blockdev_insert_anon_medium(), which is called for the
QMP commands 'blockdev-insert-medium' and 'blockdev-change-medium', to
correctly take the lock.

Cc: [e-mail]
Fixes: https://issues.redhat.com/browse/RHEL-3922
Fixes: c066e808e11a5c181b625537b6c78e0de27a4801
Signed-off-by: Kevin Wolf <[e-mail]>
Message-ID: <[e-mail]>
Reviewed-by: Hanna Czenczek <[e-mail]>
Signed-off-by: Kevin Wolf <[e-mail]>
---
 block/qapi-sysemu.c | 5 +++++
 1 file changed, 5 insertions(+)

Patch

diff --git a/block/qapi-sysemu.c b/block/qapi-sysemu.c
index 3f614cbc04..1618cd225a 100644
--- a/block/qapi-sysemu.c
+++ b/block/qapi-sysemu.c
@@ -237,6 +237,7 @@  static void qmp_blockdev_insert_anon_medium(BlockBackend *blk,
                                             BlockDriverState *bs, Error **errp)
 {
     Error *local_err = NULL;
+    AioContext *ctx;
     bool has_device;
     int ret;
 
@@ -258,7 +259,11 @@  static void qmp_blockdev_insert_anon_medium(BlockBackend *blk,
         return;
     }
 
+    ctx = bdrv_get_aio_context(bs);
+    aio_context_acquire(ctx);
     ret = blk_insert_bs(blk, bs, errp);
+    aio_context_release(ctx);
+
     if (ret < 0) {
         return;
     }