From mboxrd@z Thu Jan 1 00:00:00 1970 From: Abhishek Sahu Subject: Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection Date: Mon, 23 Apr 2018 11:59:46 +0530 Message-ID: <3699eb1ef15c63a4ea1490be7308d3dd@codeaurora.org> References: <1522845745-6624-1-git-send-email-absahu@codeaurora.org> <1522845745-6624-5-git-send-email-absahu@codeaurora.org> <20180410111220.3873a24c@xps13> <20180422182532.221747b6@xps13> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180422182532.221747b6@xps13> Sender: linux-kernel-owner@vger.kernel.org To: Miquel Raynal Cc: Boris Brezillon , Archit Taneja , Richard Weinberger , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Marek Vasut , linux-mtd@lists.infradead.org, Cyrille Pitchen , Andy Gross , Brian Norris , David Woodhouse List-Id: linux-arm-msm@vger.kernel.org On 2018-04-22 21:55, Miquel Raynal wrote: > Hi Abhishek, > > On Thu, 12 Apr 2018 12:24:16 +0530, Abhishek Sahu > wrote: > >> On 2018-04-10 14:42, Miquel Raynal wrote: >> > Hi Abhishek, >> > > On Wed, 4 Apr 2018 18:12:20 +0530, Abhishek Sahu >> > wrote: >> > >> parse_read_errors can be called with only oob buf also in which >> >> case data_buf will be NULL. If data_buf is NULL, then don’t >> >> treat this page as completely erased in case of ECC uncorrectable >> >> error. >> >> >> Signed-off-by: Abhishek Sahu >> >> --- >> >> drivers/mtd/nand/qcom_nandc.c | 7 +++++-- >> >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> >> diff --git a/drivers/mtd/nand/qcom_nandc.c >> b/drivers/mtd/nand/qcom_nandc.c >> >> index 57c16a6..0ebcc55 100644 >> >> --- a/drivers/mtd/nand/qcom_nandc.c >> >> +++ b/drivers/mtd/nand/qcom_nandc.c >> >> @@ -1607,9 +1607,11 @@ static int parse_read_errors(struct >> qcom_nand_host *host, u8 *data_buf, >> >> if (host->bch_enabled) { >> >> erased = (erased_cw & ERASED_CW) == ERASED_CW ? >> >> true : false; >> > > Why the parse_read_errors() function could not be called without >> > data_buf when using BCH? Are you sure the situation can only happen >> > without it? >> > >> host->bch_enabled case is different where controller itself tells >> regarding erased page in status register. >> >> > Would the following apply here too, with a: >> > >> erased_chunk_check_and_fixup will be used only for 4 bit RS ECC >> code in which there is no support from HW for erased page detection >> and we need to check few data bytes value. > > So please explain this with a comment. > > Thanks, > Miquèl Sure Miquel. I will do the same and update the patch with more comments. Thanks, Abhishek