| Message ID | 20170714120720.906842-1-arnd@arndb.de |
|---|---|
| Headers | show |
| Series | gcc-7 -Wformat-* warnings | expand |
On Fri, Jul 14, 2017 at 02:07:14PM +0200, Arnd Bergmann wrote: > gcc-7 points out that a negative port_num value would overflow > the string buffer: > > drivers/infiniband/hw/mlx4/sysfs.c: In function 'mlx4_ib_device_register_sysfs': > drivers/infiniband/hw/mlx4/sysfs.c:251:16: error: 'sprintf' may write a terminating nul past the end of the destination [-Werror=format-overflow=] > drivers/infiniband/hw/mlx4/sysfs.c:251:2: note: 'sprintf' output between 2 and 11 bytes into a destination of size 10 > drivers/infiniband/hw/mlx4/sysfs.c:303:17: error: 'sprintf' may write a terminating nul past the end of the destination [-Werror=format-overflow=] > drivers/infiniband/hw/mlx4/sysfs.c:303:3: note: 'sprintf' output between 2 and 11 bytes into a destination of size 10 > > While we should be able to assume that port_num is positive here, > making the buffer one byte longer has no downsides and avoids the > warning. > > Fixes: c1e7e466120b ("IB/mlx4: Add iov directory in sysfs under the ib device") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/infiniband/hw/mlx4/sysfs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Thanks, Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
This series addresses all warnings that gcc-7 introduces for -Wformat-overflow= and turns off the -Wformat-truncation by default (they remain enabled with "make W=1"). The -Wformat-overflow patches take varying approaches: - When the final use of the buffer is not limited and we print into an intermediate variable on the stack, I generally make the temporary buffer slightly larger to accomodate all theoretically possible values. Usually the code is already correct for all expected values, but gcc doesn't see that. - In some cases, we use a fixed-length buffer as the %s input for an sprintf to another buffer of the same length. Here I could make the first buffer slightly smaller so that gcc can prove the copies to be correct. - In cases where the output buffer is required to have a fixed length, I use snprintf() instead of sprintf(). This turns the overflow warning into a truncation warning that is then ignored. Here it would be much nicer to have a way to tell the compiler what the maximum expected length is, but I couldn't figure out a way to actually shut up the truncation warning completely. Any ideas would be welcome. Please review and apply as needed. Arnd Arnd Bergmann (22): kbuild: disable -Wformat-truncation warnings by default scsi: megaraid: fix format-overflow warning scsi: mpt3sas: fix format overflow warning scsi: fusion: fix string overflow warning scsi: gdth: avoid buffer overflow warning scsi: fnic: fix format string overflow warning scsi: gdth: increase the procfs event buffer size isdn: divert: fix sprintf buffer overflow warning net: niu: fix format string overflow warning: bnx2x: fix format overflow warning net: thunder_bgx: avoid format string overflow warning vmxnet3: avoid format strint overflow warning liquidio: fix possible eeprom format string overflow [media] usbvision-i2c: fix format overflow warning hwmon: applesmc: fix format string overflow x86: intel-mid: fix a format string overflow warning platform/x86: alienware-wmi: fix format string overflow warning gpio: acpi: fix string overflow for large pin numbers block: DAC960: shut up format-overflow warning sound: pci: avoid string overflow warnings fscache: fix fscache_objlist_show format processing IB/mlx4: fix sprintf format warning .../intel-mid/device_libs/platform_max7315.c | 6 ++++-- drivers/block/DAC960.c | 12 +++++++---- drivers/gpio/gpiolib-acpi.c | 2 +- drivers/hwmon/applesmc.c | 2 +- drivers/infiniband/hw/mlx4/sysfs.c | 2 +- drivers/isdn/divert/isdn_divert.c | 25 +++++++++++----------- drivers/media/usb/usbvision/usbvision-i2c.c | 4 ++-- drivers/message/fusion/mptbase.c | 2 +- .../net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c | 3 ++- drivers/net/ethernet/cavium/liquidio/lio_ethtool.c | 2 +- drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 2 +- drivers/net/ethernet/sun/niu.c | 4 ++-- drivers/net/vmxnet3/vmxnet3_int.h | 2 +- drivers/platform/x86/alienware-wmi.c | 2 +- drivers/scsi/fnic/fnic.h | 2 +- drivers/scsi/gdth.c | 2 +- drivers/scsi/gdth_proc.c | 2 +- drivers/scsi/megaraid.c | 6 ++++-- drivers/scsi/mpt3sas/mpt3sas_base.h | 2 +- fs/fscache/object-list.c | 3 ++- scripts/Makefile.extrawarn | 3 +++ sound/pci/mixart/mixart.h | 4 ++-- sound/pci/pcxhr/pcxhr.h | 4 ++-- sound/pci/rme9652/hdspm.c | 2 +- 24 files changed, 57 insertions(+), 43 deletions(-) -- 2.9.0