HID: picolcd: Avoid compile warning/error triggered by copy_from_user()
commit8c4e708d01424f88afde64a96ffd05146c9978b8
authorBruno Prémont <bonbons@linux-vserver.org>
Wed, 4 May 2011 19:08:42 +0000 (4 21:08 +0200)
committerJiri Kosina <jkosina@suse.cz>
Thu, 5 May 2011 11:45:52 +0000 (5 13:45 +0200)
treef341d2533527c7eb3e443f0bb0cfc16529bccdde
parent6d67c110ab204bc4c2f4f3e368b8d7cf1f38a4f8
HID: picolcd: Avoid compile warning/error triggered by copy_from_user()

With CONFIG_DEBUG_STRICT_USER_COPY_CHECKS=y compilation of PicoLCD
driver fails on copy_from_user(), without it a warning is generated:

  CC [M]  drivers/hid/hid-picolcd.o
In file included from /usr/src/linux-2.6/arch/x86/include/asm/uaccess.h:571,
                 from /usr/src/linux-2.6/arch/x86/include/asm/sections.h:5,
                 from /usr/src/linux-2.6/arch/x86/include/asm/hw_irq.h:26,
                 from /usr/src/linux-2.6/include/linux/irq.h:359,
                 from /usr/src/linux-2.6/arch/x86/include/asm/hardirq.h:5,
                 from /usr/src/linux-2.6/include/linux/hardirq.h:7,
                 from /usr/src/linux-2.6/include/linux/interrupt.h:12,
                 from /usr/src/linux-2.6/include/linux/usb.h:15,
                 from /usr/src/linux-2.6/drivers/hid/hid-picolcd.c:25:
In function 'copy_from_user',
    inlined from 'picolcd_debug_eeprom_write' at drivers/hid/hid-picolcd.c:1592:
arch/x86/include/asm/uaccess_32.h:212: error: call to 'copy_from_user_overflow' declared with attribute error: copy_from_user() buffer size is not provably correct

gcc-4.4.5 is not able to track size calculation when it is stored into
a variable, thus tell copy_from_user() maximum size via
min(*max-size*, *effective-size*) explicitly and inline how much to copy
at most.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
drivers/hid/hid-picolcd.c