From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miquel Raynal Subject: Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection Date: Sun, 22 Apr 2018 18:25:32 +0200 Message-ID: <20180422182532.221747b6@xps13> References: <1522845745-6624-1-git-send-email-absahu@codeaurora.org> <1522845745-6624-5-git-send-email-absahu@codeaurora.org> <20180410111220.3873a24c@xps13> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Abhishek Sahu 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 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