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firmware_loader: fix use-after-free in firmware_fallback_sysfs
commit75d95e2e39
upstream. This use-after-free happens when a fw_priv object has been freed but hasn't been removed from the pending list (pending_fw_head). The next time fw_load_sysfs_fallback tries to insert into the list, it ends up accessing the pending_list member of the previously freed fw_priv. The root cause here is that all code paths that abort the fw load don't delete it from the pending list. For example: _request_firmware() -> fw_abort_batch_reqs() -> fw_state_aborted() To fix this, delete the fw_priv from the list in __fw_set_state() if the new state is DONE or ABORTED. This way, all aborts will remove the fw_priv from the list. Accordingly, remove calls to list_del_init that were being made before calling fw_state_(aborted|done). Also, in fw_load_sysfs_fallback, don't add the fw_priv to the pending list if it is already aborted. Instead, just jump out and return early. Fixes:bcfbd3523f
("firmware: fix a double abort case with fw_load_sysfs_fallback") Cc: stable <stable@vger.kernel.org> Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com> Link: https://lore.kernel.org/r/20210728085107.4141-3-mail@anirudhrb.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
1deb6b9030
commit
d09639528b
3 changed files with 19 additions and 5 deletions
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@ -86,12 +86,11 @@ static void __fw_load_abort(struct fw_priv *fw_priv)
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{
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/*
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* There is a small window in which user can write to 'loading'
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* between loading done and disappearance of 'loading'
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* between loading done/aborted and disappearance of 'loading'
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*/
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if (fw_sysfs_done(fw_priv))
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if (fw_state_is_aborted(fw_priv) || fw_sysfs_done(fw_priv))
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return;
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list_del_init(&fw_priv->pending_list);
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fw_state_aborted(fw_priv);
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}
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@ -277,7 +276,6 @@ static ssize_t firmware_loading_store(struct device *dev,
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* Same logic as fw_load_abort, only the DONE bit
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* is ignored and we set ABORT only on failure.
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*/
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list_del_init(&fw_priv->pending_list);
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if (rc) {
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fw_state_aborted(fw_priv);
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written = rc;
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@ -512,6 +510,11 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs,
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}
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mutex_lock(&fw_lock);
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if (fw_state_is_aborted(fw_priv)) {
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mutex_unlock(&fw_lock);
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retval = -EINTR;
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goto out;
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}
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list_add(&fw_priv->pending_list, &pending_fw_head);
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mutex_unlock(&fw_lock);
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@ -537,6 +540,7 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs,
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} else if (fw_priv->is_paged_buf && !fw_priv->data)
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retval = -ENOMEM;
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out:
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device_del(f_dev);
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err_put_dev:
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put_device(f_dev);
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@ -108,8 +108,16 @@ static inline void __fw_state_set(struct fw_priv *fw_priv,
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WRITE_ONCE(fw_st->status, status);
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if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED)
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if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED) {
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#ifdef CONFIG_FW_LOADER_USER_HELPER
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/*
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* Doing this here ensures that the fw_priv is deleted from
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* the pending list in all abort/done paths.
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*/
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list_del_init(&fw_priv->pending_list);
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#endif
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complete_all(&fw_st->completion);
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}
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}
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static inline void fw_state_aborted(struct fw_priv *fw_priv)
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@ -747,8 +747,10 @@ static void fw_abort_batch_reqs(struct firmware *fw)
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return;
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fw_priv = fw->priv;
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mutex_lock(&fw_lock);
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if (!fw_state_is_aborted(fw_priv))
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fw_state_aborted(fw_priv);
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mutex_unlock(&fw_lock);
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}
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/* called from request_firmware() and request_firmware_work_func() */
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