linux-kernel - Re: [PATCHv3 1/4] zram: introduce writeback bio batching support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ysxyj7q5fuwfbvbh2o5ewsl4plzaaw2wcvn3qemjgzz43hvboq@d2k736awhhpi>
Date: Tue, 18 Nov 2025 12:47:17 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Yuwen Chen <ywen.chen@...mail.com>
Cc: senozhatsky@...omium.org, akpm@...ux-foundation.org, 
	bgeffon@...gle.com, licayy@...look.com, linux-block@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, minchan@...gle.com, minchan@...nel.org, 
	richardycc@...gle.com
Subject: Re: [PATCHv3 1/4] zram: introduce writeback bio batching support

On (25/11/18 11:36), Yuwen Chen wrote:
> On Tue, 18 Nov 2025 11:18:56 +0800, Yuwen Chen wrote:
> >> +	/*
> >> +	 * We release slot lock during writeback so slot can change under us:
> >> +	 * slot_free() or slot_free() and zram_write_page(). In both cases
> >> +	 * slot loses ZRAM_PP_SLOT flag. No concurrent post-processing can
> >> +	 * set ZRAM_PP_SLOT on such slots until current post-processing
> >> +	 * finishes.
> >> +	 */
> >> +	if (!zram_test_flag(zram, index, ZRAM_PP_SLOT))
> >> +		goto out;
> >In this place, the index may be leaked.
> 
> To be precise, blk_idx may be leaked.

Ah, I see what you mean. Agreed.

I guess I'll just send out v4 later today, given that we have two
fixups in the queue already.

---
 drivers/block/zram/zram_drv.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 0a5f11e0c523..8e91dc071b65 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -886,6 +886,7 @@ static int zram_writeback_complete(struct zram *zram, struct zram_wb_req *req)
 		 * (if enabled).
 		 */
 		zram_account_writeback_rollback(zram);
+		free_block_bdev(zram, req->blk_idx);
 		return err;
 	}
 
@@ -898,8 +899,10 @@ static int zram_writeback_complete(struct zram *zram, struct zram_wb_req *req)
 	 * set ZRAM_PP_SLOT on such slots until current post-processing
 	 * finishes.
 	 */
-	if (!zram_test_flag(zram, index, ZRAM_PP_SLOT))
+	if (!zram_test_flag(zram, index, ZRAM_PP_SLOT)) {
+		free_block_bdev(zram, req->blk_idx);
 		goto out;
+	}
 
 	zram_free_page(zram, index);
 	zram_set_flag(zram, index, ZRAM_WB);
-- 
2.52.0.rc1.455.g30608eb744-goog