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h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=hhLcH25zBEeFZnu62oWWEwWX3SBL12AvHTTzrBe7cArKFt60oCM3UOaDhEm2LyQuw 7Zsxa0NwlXfO4UYtl45Ek3QApoSaqFgNpvg+rYmv64mCbCHLTs8itApI8U8xPvmnmb ju7L77iWuVd5Mll+moPFg8NR5TsBUcAneSnVLNxWiN7dThxljeUDvPkXsV2etwYbtH lfAm/R7RcIankZar4/BS9DF+JVhJlFrYp1mF7XhKypeFs9ISuiqA4MHkSfCy9v30lo AJgkjaTU3SsF0vvAXuzk/32a/yqGgIKGg4c+Ju1X8bHiJd4ZTXvubrzsR0EoT9BLe+ upVUh6+mo7I7w== From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 4/5] i3c: master: Validate GET CCC payload length and retry Direct GET once Reply-To: sashiko-reviews@lists.linux.dev To: tze.yee.ng@altera.com Cc: imx@lists.linux.dev, "Alexandre Belloni" , Frank.Li@kernel.org, linux-i3c@lists.infradead.org In-Reply-To: References: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 08 Jul 2026 10:01:41 +0000 Message-Id: <20260708100141.EAE5D1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: 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Sashiko AI review found 2 potential issue(= s) to consider: New issues: - [Medium] Indiscriminate retries of internal kernel software errors during= I3C CCC GET commands. Pre-existing issues: - [High] renesas_i3c_rx_isr overwrites rather than appends to cmd->rx_buf, = corrupting long read transfers and causing FIFO underflows. -- --- Patch [4]: [PATCH v6 4/5] i3c: master: Validate GET CCC payload length = and retry Direct GET once --- commit 0493e80008c19d117849be20fe713d3e08ab598e Author: Adrian Ng Ho Yin i3c: master: Validate GET CCC payload length and retry Direct GET once This commit adds retry logic for Direct GET CCC commands and validates the payload length of GET CCCs after a successful transfer. Failed Direct GET CCCs are retried up to cmd->retries times when the driver reports failure or an I3C error. > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > index 3666d011f10ea..965d74e6bf166 100644 > --- a/drivers/i3c/master.c > +++ b/drivers/i3c/master.c [ ... ] > @@ -1005,7 +1037,25 @@ static int i3c_master_send_ccc_cmd_locked(struct i= 3c_master_controller *master, > !master->ops->supports_ccc_cmd(master, cmd)) > return -EOPNOTSUPP; > =20 > - return master->ops->send_ccc_cmd(master, cmd); > + max_attempts =3D cmd->retries + 1; > + ret =3D -EIO; > + for (attempt =3D 0; attempt < max_attempts; attempt++) { > + unsigned int i; > + > + if (cmd->rnw) > + for (i =3D 0; i < cmd->ndests; i++) > + cmd->dests[i].payload.actual_len =3D 0; > + > + cmd->err =3D I3C_ERROR_UNKNOWN; > + ret =3D master->ops->send_ccc_cmd(master, cmd); > + if (!ret && cmd->err =3D=3D I3C_ERROR_UNKNOWN) > + break; [Severity: Medium] Does this loop also retry internal kernel software errors? If a host software error occurs (for example, -ENOMEM during DMA descriptor allocation, or -EOPNOTSUPP), master->ops->send_ccc_cmd() will return the error code. This bypasses the !ret break condition, causing the loop to retry indiscriminately. Should the loop explicitly distinguish between bus-level I3C errors that need retries and local software errors that should immediately abort? > + } > + > + if (!ret) > + ret =3D i3c_ccc_validate_payload_len(cmd); > + > + return ret; > } [ ... ] While reviewing the retries for GET CCC commands, I noticed a separate issue in the Renesas I3C driver's receive interrupt handler: drivers/i3c/master/renesas-i3c.c:renesas_i3c_rx_isr() { ... } else { read_bytes =3D NDBSTLV0_RDBLV(renesas_readl(i3c->regs, NDBSTLV0)) *= sizeof(u32); i3c_readl_fifo(i3c->regs + NTDTBP0, cmd->rx_buf, read_bytes); cmd->rx_count =3D read_bytes; } ... } [Severity: High] This isn't a bug introduced by this patch, but does this overwrite the receive buffer rather than appending to it? When an I3C read transfer exceeds the FIFO threshold, renesas_i3c_rx_isr() fires multiple times. Instead of appending received bytes to cmd->rx_buf + cmd->rx_count and accumulating cmd->rx_count +=3D read_bytes,= it writes to the base address of cmd->rx_buf and resets cmd->rx_count. Later, renesas_i3c_resp_isr() calculates bytes_remaining =3D data_len - cmd->rx_count. Because rx_count only reflects the size of the last chunk, bytes_remaining exceeds the actual data left in the FIFO, which could cause an underflow and read garbage data. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/cover.1783493867.gi= t.tze.yee.ng@altera.com?part=3D4