linux-kernel - Re: [PATCH] mtk-sd: Fix a pagefault in dma_unmap

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: <yf7ehbrvjj46xl7hkjukygnvy5z3ez43ewqch2mksx2lmkd5of@kthk42zpjabq>
Date: Thu, 5 Jun 2025 10:14:15 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Chaotian Jing <chaotian.jing@...iatek.com>, 
	Ulf Hansson <ulf.hansson@...aro.org>, Matthias Brugger <matthias.bgg@...il.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] mtk-sd: Fix a pagefault in dma_unmap_sg() for not
 prepared data

On (25/06/05 10:07), Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> mtk-msdc driver causes a kernel crash after swiotlb buffer is full.
> 
> ---
> mtk-msdc 11240000.mmc: swiotlb buffer is full (sz: 16384 bytes), total 32768 (slots), used 32732 (slots)
> mtk-msdc 11240000.mmc: msdc_track_cmd_data: cmd=18 arg=0397A6F8; host->error=0x00000004
> Unable to handle kernel paging request at virtual address ffffffffc0001fc0
> ---
> 
> When swiotlb buffer is full, the dma_map_sg() returns 0 to
> msdc_prepare_data(), but it does not check it and sets the
> MSDC_PREPARE_FLAG.
> 
> swiotlb_tbl_map_single() /* prints "swiotlb buffer is full" */
>   <-swiotlb_map()
>     <-dma_direct_map_page()
>       <-dma_direct_map_sg()
>         <-__dma_map_sg_attrs()
>           <-dma_map_sg_attrs()
>             <-dma_map_sg()  /* returns 0 (pages mapped) */
>               <-msdc_prepare_data()
> 
> Then, the msdc_unprepare_data() checks MSDC_PREPARE_FLAG and calls
> dma_unmap_sg() with unmapped pages. It causes a page fault.
> 
> To fix this problem, Do not set MSDC_PREPARE_FLAG if dma_map_sg()
> fails because this is not prepared.
> 
> Fixes: 208489032bdd ("mmc: mediatek: Add Mediatek MMC driver")
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Tested-by: Sergey Senozhatsky <senozhatsky@...omium.org>