From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C98CD882B for ; Fri, 10 Mar 2023 15:13:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E63EC433EF; Fri, 10 Mar 2023 15:13:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678461199; bh=rLWiCETR7DLdPDV5hE63q9oyGNn+uqL0W9kDx5oLStg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qXY3uRv89crQynKIchOJq8trrxuelvDKQQjlbTW0y8jzbeStH2zsOMcynDA4feFwY nOXDqkb0gOtO8+HvG3jAgbDZaAcUWmg67igOi4tYVhF20yOKE4ppD1gDG/kcgigSOj tlyR/v9pmGHDbehRGFuIS06EOw7MzEQlerLf1x4Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhihao Cheng , Richard Weinberger , Sasha Levin Subject: [PATCH 5.15 028/136] ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed Date: Fri, 10 Mar 2023 14:42:30 +0100 Message-Id: <20230310133707.847348712@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133706.811226272@linuxfoundation.org> References: <20230310133706.811226272@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Zhihao Cheng [ Upstream commit 4d57a7333e26040f2b583983e1970d9d460e56b0 ] Following process will trigger an infinite loop in ubi_wl_put_peb(): ubifs_bgt ubi_bgt ubifs_leb_unmap ubi_leb_unmap ubi_eba_unmap_leb ubi_wl_put_peb wear_leveling_worker e1 = rb_entry(rb_first(&ubi->used) e2 = get_peb_for_wl(ubi) ubi_io_read_vid_hdr // return err (flash fault) out_error: ubi->move_from = ubi->move_to = NULL wl_entry_destroy(ubi, e1) ubi->lookuptbl[e->pnum] = NULL retry: e = ubi->lookuptbl[pnum]; // return NULL if (e == ubi->move_from) { // NULL == NULL gets true goto retry; // infinite loop !!! $ top PID USER PR NI VIRT RES SHR S %CPU %MEM COMMAND 7676 root 20 0 0 0 0 R 100.0 0.0 ubifs_bgt0_0 Fix it by: 1) Letting ubi_wl_put_peb() returns directly if wearl leveling entry has been removed from 'ubi->lookuptbl'. 2) Using 'ubi->wl_lock' protecting wl entry deletion to preventing an use-after-free problem for wl entry in ubi_wl_put_peb(). Fetch a reproducer in [Link]. Fixes: 43f9b25a9cdd7b1 ("UBI: bugfix: protect from volume removal") Fixes: ee59ba8b064f692 ("UBI: Fix stale pointers in ubi->lookuptbl") Link: https://bugzilla.kernel.org/show_bug.cgi?id=216111 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- drivers/mtd/ubi/wl.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c index 4a672e925d869..2ee0e60c43c2e 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -972,11 +972,11 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk, spin_lock(&ubi->wl_lock); ubi->move_from = ubi->move_to = NULL; ubi->move_to_put = ubi->wl_scheduled = 0; + wl_entry_destroy(ubi, e1); + wl_entry_destroy(ubi, e2); spin_unlock(&ubi->wl_lock); ubi_free_vid_buf(vidb); - wl_entry_destroy(ubi, e1); - wl_entry_destroy(ubi, e2); out_ro: ubi_ro_mode(ubi); @@ -1250,6 +1250,18 @@ int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum, retry: spin_lock(&ubi->wl_lock); e = ubi->lookuptbl[pnum]; + if (!e) { + /* + * This wl entry has been removed for some errors by other + * process (eg. wear leveling worker), corresponding process + * (except __erase_worker, which cannot concurrent with + * ubi_wl_put_peb) will set ubi ro_mode at the same time, + * just ignore this wl entry. + */ + spin_unlock(&ubi->wl_lock); + up_read(&ubi->fm_protect); + return 0; + } if (e == ubi->move_from) { /* * User is putting the physical eraseblock which was selected to -- 2.39.2