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Instead, store host->index_is_alias to avoid reading the parent at release time. Also, call kref_put() after mmc_request_done(), as the latter dereferences the host pointer. Fixes: 88095e7b473a ("mmc: Add new VUB300 USB-to-SD/SDIO/MMC driver") Reported-by: syzbot+f312381a95cc080992fd@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=f312381a95cc080992fd Assisted-by: opencode: deepseek v4 flash Cc: stable@vger.kernel.org Signed-off-by: Adriano Cordova --- drivers/mmc/core/host.c | 3 ++- drivers/mmc/host/vub300.c | 4 ++-- include/linux/mmc/host.h | 1 + 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index b7ce3137d452..542bb033c6da 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -67,7 +67,7 @@ static void mmc_host_classdev_release(struct device *dev) { struct mmc_host *host = cls_dev_to_mmc_host(dev); wakeup_source_unregister(host->ws); - if (of_alias_get_id(host->parent->of_node, "mmc") < 0) + if (!host->index_is_alias) ida_free(&mmc_host_ida, host->index); kfree(host); } @@ -538,6 +538,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) } host->index = index; + host->index_is_alias = (alias_id >= 0); dev_set_name(&host->class_dev, "mmc%d", host->index); host->ws = wakeup_source_register(NULL, dev_name(&host->class_dev)); diff --git a/drivers/mmc/host/vub300.c b/drivers/mmc/host/vub300.c index 2dae474dcd06..c87c54aa0e99 100644 --- a/drivers/mmc/host/vub300.c +++ b/drivers/mmc/host/vub300.c @@ -1794,8 +1794,8 @@ static void vub300_cmndwork_thread(struct work_struct *work) construct_request_response(vub300, cmd); vub300->resp_len = 0; mutex_unlock(&vub300->cmd_mutex); - kref_put(&vub300->kref, vub300_delete); mmc_request_done(vub300->mmc, req); + kref_put(&vub300->kref, vub300_delete); return; } } @@ -1946,8 +1946,8 @@ static void vub300_mmc_request(struct mmc_host *mmc, struct mmc_request *req) satisfy_request_from_offloaded_data(vub300, cmd)) { cmd->error = 0; mutex_unlock(&vub300->cmd_mutex); - kref_put(&vub300->kref, vub300_delete); mmc_request_done(mmc, req); + kref_put(&vub300->kref, vub300_delete); return; } else { vub300->cmd = cmd; diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index ba84f02c2a10..165d24104d3c 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -356,6 +356,7 @@ struct mmc_host { struct device *parent; struct device class_dev; int index; + bool index_is_alias; const struct mmc_host_ops *ops; struct mmc_pwrseq *pwrseq; unsigned int f_min; -- 2.51.0