linux-kernel - Re: [PATCH v3] zram: don't free statically defined names

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Message-ID: <20240924051745.GK38742@google.com>
Date: Tue, 24 Sep 2024 14:17:45 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Skvortsov <andrej.skvortzov@...il.com>,
	Venkat Rao Bagalkote <venkat88@...ux.vnet.ibm.com>,
	Minchan Kim <minchan@...nel.org>, Jens Axboe <axboe@...nel.dk>,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v3] zram: don't free statically defined names

On (24/09/24 10:42), Sergey Senozhatsky wrote:
> On (24/09/23 19:48), Andrey Skvortsov wrote:
> > When CONFIG_ZRAM_MULTI_COMP isn't set ZRAM_SECONDARY_COMP can hold
> > default_compressor, because it's the same offset as ZRAM_PRIMARY_COMP,
> > so we need to make sure that we don't attempt to kfree() the
> > statically defined compressor name.
> > 
> > This is detected by KASAN.
> > 
> > ==================================================================
> >   Call trace:
> >    kfree+0x60/0x3a0
> >    zram_destroy_comps+0x98/0x198 [zram]
> >    zram_reset_device+0x22c/0x4a8 [zram]
> >    reset_store+0x1bc/0x2d8 [zram]
> >    dev_attr_store+0x44/0x80
> >    sysfs_kf_write+0xfc/0x188
> >    kernfs_fop_write_iter+0x28c/0x428
> >    vfs_write+0x4dc/0x9b8
> >    ksys_write+0x100/0x1f8
> >    __arm64_sys_write+0x74/0xb8
> >    invoke_syscall+0xd8/0x260
> >    el0_svc_common.constprop.0+0xb4/0x240
> >    do_el0_svc+0x48/0x68
> >    el0_svc+0x40/0xc8
> >    el0t_64_sync_handler+0x120/0x130
> >    el0t_64_sync+0x190/0x198
> > ==================================================================
> > 
> > Signed-off-by: Andrey Skvortsov <andrej.skvortzov@...il.com>
> > Fixes: 684826f8271a ("zram: free secondary algorithms names")
> > Cc: <stable@...r.kernel.org>
> 
> Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>

As a minor side note, I'd still prefer to drop that backtrace from
the commit message - we know that reset_store() is called from sysfs
write, there is nothing new (nor important) in that call trace.