| Message ID | 20210807041859.579409-2-damien.lemoal@wdc.com |
|---|---|
| State | New |
| Headers | show |
| Series | libata cleanups and improvements | expand |
On 8/7/21 6:18 AM, Damien Le Moal wrote: > Avoid static checkers warnings about a potential NULL pointer > dereference for the port info variable pi. To do so, test that at least > one port info is available on entry to ata_host_alloc_pinfo() and start > the ata port initialization for loop with pi initialized to a non-NULL > pointer. Within the for loop, get the next port info (if it is not NULL) > after initializing the ata port using the previous port info. > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> > --- > drivers/ata/libata-core.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c > index 61c762961ca8..b17e161c07e2 100644 > --- a/drivers/ata/libata-core.c > +++ b/drivers/ata/libata-core.c > @@ -5441,16 +5441,17 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, > struct ata_host *host; > int i, j; > > + /* We must have at least one port info */ > + if (!ppi[0]) > + return NULL; > + > host = ata_host_alloc(dev, n_ports); > if (!host) > return NULL; > > - for (i = 0, j = 0, pi = NULL; i < host->n_ports; i++) { > + for (i = 0, j = 0, pi = ppi[0]; i < host->n_ports; i++) { > struct ata_port *ap = host->ports[i]; > > - if (ppi[j]) > - pi = ppi[j++]; > - > ap->pio_mask = pi->pio_mask; > ap->mwdma_mask = pi->mwdma_mask; > ap->udma_mask = pi->udma_mask; > @@ -5458,8 +5459,13 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, > ap->link.flags |= pi->link_flags; > ap->ops = pi->port_ops; > > - if (!host->ops && (pi->port_ops != &ata_dummy_port_ops)) > + if (!host->ops && pi->port_ops != &ata_dummy_port_ops) > host->ops = pi->port_ops; > + > + if (ppi[j + 1]) { > + j++; > + pi = ppi[j]; > + } > } > > return host; > This requires a comment as to why this is necessary. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
On 2021/08/09 15:09, Hannes Reinecke wrote: > On 8/7/21 6:18 AM, Damien Le Moal wrote: >> Avoid static checkers warnings about a potential NULL pointer >> dereference for the port info variable pi. To do so, test that at least >> one port info is available on entry to ata_host_alloc_pinfo() and start >> the ata port initialization for loop with pi initialized to a non-NULL >> pointer. Within the for loop, get the next port info (if it is not NULL) >> after initializing the ata port using the previous port info. >> >> Reported-by: kernel test robot <lkp@intel.com> >> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> >> --- >> drivers/ata/libata-core.c | 16 +++++++++++----- >> 1 file changed, 11 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c >> index 61c762961ca8..b17e161c07e2 100644 >> --- a/drivers/ata/libata-core.c >> +++ b/drivers/ata/libata-core.c >> @@ -5441,16 +5441,17 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, >> struct ata_host *host; >> int i, j; >> >> + /* We must have at least one port info */ >> + if (!ppi[0]) >> + return NULL; >> + >> host = ata_host_alloc(dev, n_ports); >> if (!host) >> return NULL; >> >> - for (i = 0, j = 0, pi = NULL; i < host->n_ports; i++) { >> + for (i = 0, j = 0, pi = ppi[0]; i < host->n_ports; i++) { >> struct ata_port *ap = host->ports[i]; >> >> - if (ppi[j]) >> - pi = ppi[j++]; >> - >> ap->pio_mask = pi->pio_mask; >> ap->mwdma_mask = pi->mwdma_mask; >> ap->udma_mask = pi->udma_mask; >> @@ -5458,8 +5459,13 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, >> ap->link.flags |= pi->link_flags; >> ap->ops = pi->port_ops; >> >> - if (!host->ops && (pi->port_ops != &ata_dummy_port_ops)) >> + if (!host->ops && pi->port_ops != &ata_dummy_port_ops) >> host->ops = pi->port_ops; >> + >> + if (ppi[j + 1]) { >> + j++; >> + pi = ppi[j]; >> + } >> } >> >> return host; >> > This requires a comment as to why this is necessary. You lost me... About what exactly ? If it is about how ppi must be used to initialize pi, the function kdoc comment does explain it. Note that the last hunk is wrong: there is a potential out of bound array reference. The condition should be: if (j < nr_ports - 1 && ppi[j + 1]) { Will send an update with that. > > Cheers, > > Hannes >
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 61c762961ca8..b17e161c07e2 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -5441,16 +5441,17 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, struct ata_host *host; int i, j; + /* We must have at least one port info */ + if (!ppi[0]) + return NULL; + host = ata_host_alloc(dev, n_ports); if (!host) return NULL; - for (i = 0, j = 0, pi = NULL; i < host->n_ports; i++) { + for (i = 0, j = 0, pi = ppi[0]; i < host->n_ports; i++) { struct ata_port *ap = host->ports[i]; - if (ppi[j]) - pi = ppi[j++]; - ap->pio_mask = pi->pio_mask; ap->mwdma_mask = pi->mwdma_mask; ap->udma_mask = pi->udma_mask; @@ -5458,8 +5459,13 @@ struct ata_host *ata_host_alloc_pinfo(struct device *dev, ap->link.flags |= pi->link_flags; ap->ops = pi->port_ops; - if (!host->ops && (pi->port_ops != &ata_dummy_port_ops)) + if (!host->ops && pi->port_ops != &ata_dummy_port_ops) host->ops = pi->port_ops; + + if (ppi[j + 1]) { + j++; + pi = ppi[j]; + } } return host;
Avoid static checkers warnings about a potential NULL pointer dereference for the port info variable pi. To do so, test that at least one port info is available on entry to ata_host_alloc_pinfo() and start the ata port initialization for loop with pi initialized to a non-NULL pointer. Within the for loop, get the next port info (if it is not NULL) after initializing the ata port using the previous port info. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- drivers/ata/libata-core.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)