| Message ID | 20200226223125.GA20630@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mmc: Replace zero-length array with flexible-array member | expand |
On 27/02/20 12:31 am, Gustavo A. R. Silva wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Acked-by: Adrian Hunter <adrian.hunter@intel.com> > --- > drivers/mmc/host/sdhci-acpi.c | 2 +- > drivers/mmc/host/sdhci-cadence.c | 2 +- > drivers/mmc/host/sdhci-pci.h | 2 +- > drivers/mmc/host/sdhci-pltfm.h | 2 +- > drivers/mmc/host/sdhci.h | 2 +- > drivers/mmc/host/vub300.c | 2 +- > include/linux/mmc/host.h | 2 +- > include/linux/mmc/sdio_func.h | 2 +- > include/uapi/linux/mmc/ioctl.h | 2 +- > 9 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c > index 9651dca6863e..ea0e4fda3a9e 100644 > --- a/drivers/mmc/host/sdhci-acpi.c > +++ b/drivers/mmc/host/sdhci-acpi.c > @@ -72,7 +72,7 @@ struct sdhci_acpi_host { > const struct sdhci_acpi_slot *slot; > struct platform_device *pdev; > bool use_runtime_pm; > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > static inline void *sdhci_acpi_priv(struct sdhci_acpi_host *c) > diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c > index 5827d3751b81..9af3fe48d62f 100644 > --- a/drivers/mmc/host/sdhci-cadence.c > +++ b/drivers/mmc/host/sdhci-cadence.c > @@ -67,7 +67,7 @@ struct sdhci_cdns_priv { > void __iomem *hrs_addr; > bool enhanced_strobe; > unsigned int nr_phy_params; > - struct sdhci_cdns_phy_param phy_params[0]; > + struct sdhci_cdns_phy_param phy_params[]; > }; > > struct sdhci_cdns_phy_cfg { > diff --git a/drivers/mmc/host/sdhci-pci.h b/drivers/mmc/host/sdhci-pci.h > index 981bbbe63aff..42ccd123b046 100644 > --- a/drivers/mmc/host/sdhci-pci.h > +++ b/drivers/mmc/host/sdhci-pci.h > @@ -163,7 +163,7 @@ struct sdhci_pci_slot { > bool cd_override_level; > > void (*hw_reset)(struct sdhci_host *host); > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct sdhci_pci_chip { > diff --git a/drivers/mmc/host/sdhci-pltfm.h b/drivers/mmc/host/sdhci-pltfm.h > index 2af445b8c325..6301b81cf573 100644 > --- a/drivers/mmc/host/sdhci-pltfm.h > +++ b/drivers/mmc/host/sdhci-pltfm.h > @@ -25,7 +25,7 @@ struct sdhci_pltfm_host { > unsigned int clock; > u16 xfer_mode_shadow; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > #ifdef CONFIG_MMC_SDHCI_BIG_ENDIAN_32BIT_BYTE_SWAPPER > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h > index cac2d97782e6..249635692112 100644 > --- a/drivers/mmc/host/sdhci.h > +++ b/drivers/mmc/host/sdhci.h > @@ -614,7 +614,7 @@ struct sdhci_host { > > u64 data_timeout; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct sdhci_ops { > diff --git a/drivers/mmc/host/vub300.c b/drivers/mmc/host/vub300.c > index 6ced1b7f642f..a5a90d133f1f 100644 > --- a/drivers/mmc/host/vub300.c > +++ b/drivers/mmc/host/vub300.c > @@ -95,7 +95,7 @@ struct sd_response_header { > u8 port_number; > u8 command_type; > u8 command_index; > - u8 command_response[0]; > + u8 command_response[]; > } __packed; > > struct sd_status_header { > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index 562ed06881b0..2629329ab9f2 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -465,7 +465,7 @@ struct mmc_host { > /* Host Software Queue support */ > bool hsq_enabled; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct device_node; > diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h > index 5a177f7a83c3..fa2aaab5e57a 100644 > --- a/include/linux/mmc/sdio_func.h > +++ b/include/linux/mmc/sdio_func.h > @@ -25,7 +25,7 @@ struct sdio_func_tuple { > struct sdio_func_tuple *next; > unsigned char code; > unsigned char size; > - unsigned char data[0]; > + unsigned char data[]; > }; > > /* > diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h > index 00c08120f3ba..98e29e7f54ac 100644 > --- a/include/uapi/linux/mmc/ioctl.h > +++ b/include/uapi/linux/mmc/ioctl.h > @@ -57,7 +57,7 @@ struct mmc_ioc_cmd { > */ > struct mmc_ioc_multi_cmd { > __u64 num_of_cmds; > - struct mmc_ioc_cmd cmds[0]; > + struct mmc_ioc_cmd cmds[]; > }; > > #define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd) >
On Wed, 26 Feb 2020 at 23:28, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Applied for next, thanks! Kind regards Uffe > --- > drivers/mmc/host/sdhci-acpi.c | 2 +- > drivers/mmc/host/sdhci-cadence.c | 2 +- > drivers/mmc/host/sdhci-pci.h | 2 +- > drivers/mmc/host/sdhci-pltfm.h | 2 +- > drivers/mmc/host/sdhci.h | 2 +- > drivers/mmc/host/vub300.c | 2 +- > include/linux/mmc/host.h | 2 +- > include/linux/mmc/sdio_func.h | 2 +- > include/uapi/linux/mmc/ioctl.h | 2 +- > 9 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c > index 9651dca6863e..ea0e4fda3a9e 100644 > --- a/drivers/mmc/host/sdhci-acpi.c > +++ b/drivers/mmc/host/sdhci-acpi.c > @@ -72,7 +72,7 @@ struct sdhci_acpi_host { > const struct sdhci_acpi_slot *slot; > struct platform_device *pdev; > bool use_runtime_pm; > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > static inline void *sdhci_acpi_priv(struct sdhci_acpi_host *c) > diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c > index 5827d3751b81..9af3fe48d62f 100644 > --- a/drivers/mmc/host/sdhci-cadence.c > +++ b/drivers/mmc/host/sdhci-cadence.c > @@ -67,7 +67,7 @@ struct sdhci_cdns_priv { > void __iomem *hrs_addr; > bool enhanced_strobe; > unsigned int nr_phy_params; > - struct sdhci_cdns_phy_param phy_params[0]; > + struct sdhci_cdns_phy_param phy_params[]; > }; > > struct sdhci_cdns_phy_cfg { > diff --git a/drivers/mmc/host/sdhci-pci.h b/drivers/mmc/host/sdhci-pci.h > index 981bbbe63aff..42ccd123b046 100644 > --- a/drivers/mmc/host/sdhci-pci.h > +++ b/drivers/mmc/host/sdhci-pci.h > @@ -163,7 +163,7 @@ struct sdhci_pci_slot { > bool cd_override_level; > > void (*hw_reset)(struct sdhci_host *host); > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct sdhci_pci_chip { > diff --git a/drivers/mmc/host/sdhci-pltfm.h b/drivers/mmc/host/sdhci-pltfm.h > index 2af445b8c325..6301b81cf573 100644 > --- a/drivers/mmc/host/sdhci-pltfm.h > +++ b/drivers/mmc/host/sdhci-pltfm.h > @@ -25,7 +25,7 @@ struct sdhci_pltfm_host { > unsigned int clock; > u16 xfer_mode_shadow; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > #ifdef CONFIG_MMC_SDHCI_BIG_ENDIAN_32BIT_BYTE_SWAPPER > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h > index cac2d97782e6..249635692112 100644 > --- a/drivers/mmc/host/sdhci.h > +++ b/drivers/mmc/host/sdhci.h > @@ -614,7 +614,7 @@ struct sdhci_host { > > u64 data_timeout; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct sdhci_ops { > diff --git a/drivers/mmc/host/vub300.c b/drivers/mmc/host/vub300.c > index 6ced1b7f642f..a5a90d133f1f 100644 > --- a/drivers/mmc/host/vub300.c > +++ b/drivers/mmc/host/vub300.c > @@ -95,7 +95,7 @@ struct sd_response_header { > u8 port_number; > u8 command_type; > u8 command_index; > - u8 command_response[0]; > + u8 command_response[]; > } __packed; > > struct sd_status_header { > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index 562ed06881b0..2629329ab9f2 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -465,7 +465,7 @@ struct mmc_host { > /* Host Software Queue support */ > bool hsq_enabled; > > - unsigned long private[0] ____cacheline_aligned; > + unsigned long private[] ____cacheline_aligned; > }; > > struct device_node; > diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h > index 5a177f7a83c3..fa2aaab5e57a 100644 > --- a/include/linux/mmc/sdio_func.h > +++ b/include/linux/mmc/sdio_func.h > @@ -25,7 +25,7 @@ struct sdio_func_tuple { > struct sdio_func_tuple *next; > unsigned char code; > unsigned char size; > - unsigned char data[0]; > + unsigned char data[]; > }; > > /* > diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h > index 00c08120f3ba..98e29e7f54ac 100644 > --- a/include/uapi/linux/mmc/ioctl.h > +++ b/include/uapi/linux/mmc/ioctl.h > @@ -57,7 +57,7 @@ struct mmc_ioc_cmd { > */ > struct mmc_ioc_multi_cmd { > __u64 num_of_cmds; > - struct mmc_ioc_cmd cmds[0]; > + struct mmc_ioc_cmd cmds[]; > }; > > #define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd) > -- > 2.25.0 >
On 3/11/20 10:34, Ulf Hansson wrote: >> >> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html >> [2] https://github.com/KSPP/linux/issues/21 >> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") >> >> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > > Applied for next, thanks! > Thanks, Ulf. -- Gustavo > Kind regards > Uffe >
diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c index 9651dca6863e..ea0e4fda3a9e 100644 --- a/drivers/mmc/host/sdhci-acpi.c +++ b/drivers/mmc/host/sdhci-acpi.c @@ -72,7 +72,7 @@ struct sdhci_acpi_host { const struct sdhci_acpi_slot *slot; struct platform_device *pdev; bool use_runtime_pm; - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; static inline void *sdhci_acpi_priv(struct sdhci_acpi_host *c) diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c index 5827d3751b81..9af3fe48d62f 100644 --- a/drivers/mmc/host/sdhci-cadence.c +++ b/drivers/mmc/host/sdhci-cadence.c @@ -67,7 +67,7 @@ struct sdhci_cdns_priv { void __iomem *hrs_addr; bool enhanced_strobe; unsigned int nr_phy_params; - struct sdhci_cdns_phy_param phy_params[0]; + struct sdhci_cdns_phy_param phy_params[]; }; struct sdhci_cdns_phy_cfg { diff --git a/drivers/mmc/host/sdhci-pci.h b/drivers/mmc/host/sdhci-pci.h index 981bbbe63aff..42ccd123b046 100644 --- a/drivers/mmc/host/sdhci-pci.h +++ b/drivers/mmc/host/sdhci-pci.h @@ -163,7 +163,7 @@ struct sdhci_pci_slot { bool cd_override_level; void (*hw_reset)(struct sdhci_host *host); - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; struct sdhci_pci_chip { diff --git a/drivers/mmc/host/sdhci-pltfm.h b/drivers/mmc/host/sdhci-pltfm.h index 2af445b8c325..6301b81cf573 100644 --- a/drivers/mmc/host/sdhci-pltfm.h +++ b/drivers/mmc/host/sdhci-pltfm.h @@ -25,7 +25,7 @@ struct sdhci_pltfm_host { unsigned int clock; u16 xfer_mode_shadow; - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; #ifdef CONFIG_MMC_SDHCI_BIG_ENDIAN_32BIT_BYTE_SWAPPER diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h index cac2d97782e6..249635692112 100644 --- a/drivers/mmc/host/sdhci.h +++ b/drivers/mmc/host/sdhci.h @@ -614,7 +614,7 @@ struct sdhci_host { u64 data_timeout; - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; struct sdhci_ops { diff --git a/drivers/mmc/host/vub300.c b/drivers/mmc/host/vub300.c index 6ced1b7f642f..a5a90d133f1f 100644 --- a/drivers/mmc/host/vub300.c +++ b/drivers/mmc/host/vub300.c @@ -95,7 +95,7 @@ struct sd_response_header { u8 port_number; u8 command_type; u8 command_index; - u8 command_response[0]; + u8 command_response[]; } __packed; struct sd_status_header { diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 562ed06881b0..2629329ab9f2 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -465,7 +465,7 @@ struct mmc_host { /* Host Software Queue support */ bool hsq_enabled; - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; struct device_node; diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h index 5a177f7a83c3..fa2aaab5e57a 100644 --- a/include/linux/mmc/sdio_func.h +++ b/include/linux/mmc/sdio_func.h @@ -25,7 +25,7 @@ struct sdio_func_tuple { struct sdio_func_tuple *next; unsigned char code; unsigned char size; - unsigned char data[0]; + unsigned char data[]; }; /* diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h index 00c08120f3ba..98e29e7f54ac 100644 --- a/include/uapi/linux/mmc/ioctl.h +++ b/include/uapi/linux/mmc/ioctl.h @@ -57,7 +57,7 @@ struct mmc_ioc_cmd { */ struct mmc_ioc_multi_cmd { __u64 num_of_cmds; - struct mmc_ioc_cmd cmds[0]; + struct mmc_ioc_cmd cmds[]; }; #define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/mmc/host/sdhci-acpi.c | 2 +- drivers/mmc/host/sdhci-cadence.c | 2 +- drivers/mmc/host/sdhci-pci.h | 2 +- drivers/mmc/host/sdhci-pltfm.h | 2 +- drivers/mmc/host/sdhci.h | 2 +- drivers/mmc/host/vub300.c | 2 +- include/linux/mmc/host.h | 2 +- include/linux/mmc/sdio_func.h | 2 +- include/uapi/linux/mmc/ioctl.h | 2 +- 9 files changed, 9 insertions(+), 9 deletions(-)