On 2/16/22 07:13, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx> There are many different ways that access_ok() is defined across architectures, but in the end, they all just compare against the user_addr_max() value or they accept anything. Provide one definition that works for most architectures, checking against TASK_SIZE_MAX for user processes or skipping the check inside of uaccess_kernel() sections. For architectures without CONFIG_SET_FS(), this should be the fastest check, as it comes down to a single comparison of a pointer against a compile-time constant, while the architecture specific versions tend to do something more complex for historic reasons or get something wrong. Type checking for __user annotations is handled inconsistently across architectures, but this is easily simplified as well by using an inline function that takes a 'const void __user *' argument. A handful of callers need an extra __user annotation for this. Some architectures had trick to use 33-bit or 65-bit arithmetic on the addresses to calculate the overflow, however this simpler version uses fewer registers, which means it can produce better object code in the end despite needing a second (statically predicted) branch. Reviewed-by: Christoph Hellwig <hch@xxxxxx> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> [arm64, asm-generic] Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- arch/Kconfig | 7 ++++ arch/alpha/include/asm/uaccess.h | 34 +++------------ arch/arc/include/asm/uaccess.h | 29 ------------- arch/arm/include/asm/uaccess.h | 20 +-------- arch/arm64/include/asm/uaccess.h | 11 ++--- arch/csky/include/asm/uaccess.h | 8 ---- arch/hexagon/include/asm/uaccess.h | 25 ------------ arch/ia64/include/asm/uaccess.h | 5 +-- arch/m68k/Kconfig.cpu | 1 + arch/m68k/include/asm/uaccess.h | 19 +-------- arch/microblaze/include/asm/uaccess.h | 8 +--- arch/mips/include/asm/uaccess.h | 29 +------------ arch/nds32/include/asm/uaccess.h | 7 +--- arch/nios2/include/asm/uaccess.h | 11 +----
Acked-by: Dinh Nguyen <dinguyen@xxxxxxxxxx>
