From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Fabian Ebner Date: Wed, 25 May 2022 13:59:38 +0200 Subject: [PATCH] PVE-Backup: ensure jobs in di_list are referenced Ensures that qmp_backup_cancel doesn't pick a job that's already been freed. With unlucky timings it seems possible that: 1. job_exit -> job_completed -> job_finalize_single starts 2. pvebackup_co_complete_stream gets spawned in completion callback 3. job finalize_single finishes -> job's refcount hits zero -> job is freed 4. qmp_backup_cancel comes in and locks backup_state.backup_mutex before pvebackup_co_complete_stream can remove the job from the di_list 5. qmp_backup_cancel will pick a job that's already been freed Signed-off-by: Fabian Ebner Signed-off-by: Wolfgang Bumiller --- pve-backup.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) Index: pve-qemu-kvm-6.2.0/pve-backup.c =================================================================== --- pve-qemu-kvm-6.2.0.orig/pve-backup.c +++ pve-qemu-kvm-6.2.0/pve-backup.c @@ -316,6 +316,14 @@ static void coroutine_fn pvebackup_co_co } } + if (di->job) { + AioContext *ctx = di->job->job.aio_context; + aio_context_acquire(ctx); + job_unref(&di->job->job); + di->job = NULL; + aio_context_release(ctx); + } + // remove self from job list backup_state.di_list = g_list_remove(backup_state.di_list, di); @@ -491,9 +499,12 @@ static void create_backup_jobs_bh(void * bitmap_mode, false, NULL, &perf, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT, JOB_DEFAULT, pvebackup_complete_cb, di, backup_state.txn, &local_err); - aio_context_release(aio_context); - di->job = job; + if (job) { + job_ref(&job->job); + } + + aio_context_release(aio_context); if (!job || local_err) { error_setg(errp, "backup_job_create failed: %s", @@ -521,12 +532,16 @@ static void create_backup_jobs_bh(void * di->target = NULL; } - if (!canceled && di->job) { + if (di->job) { AioContext *ctx = di->job->job.aio_context; aio_context_acquire(ctx); - job_cancel_sync(&di->job->job, true); + if (!canceled) { + job_cancel_sync(&di->job->job, true); + canceled = true; + } + job_unref(&di->job->job); + di->job = NULL; aio_context_release(ctx); - canceled = true; } } }