From: Russell King Date: Wed, 7 Nov 2018 16:44:01 +0000 (-0500) Subject: ARM: spectre-v1: use get_user() for __get_user() X-Git-Tag: v4.9.139~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f4438f29bfbd105a4208cf194cd7f1f3e01fd666;p=platform%2Fkernel%2Flinux-amlogic.git ARM: spectre-v1: use get_user() for __get_user() Commit b1cd0a14806321721aae45f5446ed83a3647c914 upstream. Fixing __get_user() for spectre variant 1 is not sane: we would have to add address space bounds checking in order to validate that the location should be accessed, and then zero the address if found to be invalid. Since __get_user() is supposed to avoid the bounds check, and this is exactly what get_user() does, there's no point having two different implementations that are doing the same thing. So, when the Spectre workarounds are required, make __get_user() an alias of get_user(). Acked-by: Mark Rutland Signed-off-by: Russell King Signed-off-by: David A. Long Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 4a61f36c7397..7b17460127fd 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -280,6 +280,16 @@ static inline void set_fs(mm_segment_t fs) #define user_addr_max() \ (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs()) +#ifdef CONFIG_CPU_SPECTRE +/* + * When mitigating Spectre variant 1, it is not worth fixing the non- + * verifying accessors, because we need to add verification of the + * address space there. Force these to use the standard get_user() + * version instead. + */ +#define __get_user(x, ptr) get_user(x, ptr) +#else + /* * The "__xxx" versions of the user access functions do not verify the * address space - it must have been done previously with a separate @@ -296,12 +306,6 @@ static inline void set_fs(mm_segment_t fs) __gu_err; \ }) -#define __get_user_error(x, ptr, err) \ -({ \ - __get_user_err((x), (ptr), err); \ - (void) 0; \ -}) - #define __get_user_err(x, ptr, err) \ do { \ unsigned long __gu_addr = (unsigned long)(ptr); \ @@ -361,6 +365,7 @@ do { \ #define __get_user_asm_word(x, addr, err) \ __get_user_asm(x, addr, err, ldr) +#endif #define __put_user_switch(x, ptr, __err, __fn) \