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: Fiona Ebner Signed-off-by: Wolfgang Bumiller [FE: adapt for new job lock mechanism replacing AioContext locks] Signed-off-by: Fiona Ebner --- pve-backup.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/pve-backup.c b/pve-backup.c index 79d14d6a0b..67e2b99d74 100644 --- a/pve-backup.c +++ b/pve-backup.c @@ -318,6 +318,13 @@ static void coroutine_fn pvebackup_co_complete_stream(void *opaque) } } + if (di->job) { + WITH_JOB_LOCK_GUARD() { + job_unref_locked(&di->job->job); + di->job = NULL; + } + } + // remove self from job list backup_state.di_list = g_list_remove(backup_state.di_list, di); @@ -493,6 +500,11 @@ static void create_backup_jobs_bh(void *opaque) { aio_context_release(aio_context); di->job = job; + if (job) { + WITH_JOB_LOCK_GUARD() { + job_ref_locked(&job->job); + } + } if (!job || local_err) { error_setg(errp, "backup_job_create failed: %s", @@ -520,11 +532,15 @@ static void create_backup_jobs_bh(void *opaque) { di->target = NULL; } - if (!canceled && di->job) { + if (di->job) { WITH_JOB_LOCK_GUARD() { - job_cancel_sync_locked(&di->job->job, true); + if (!canceled) { + job_cancel_sync_locked(&di->job->job, true); + canceled = true; + } + job_unref_locked(&di->job->job); + di->job = NULL; } - canceled = true; } } }