From 12700c17fc286149324f92d6d380bc48e43f253d Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 15 Feb 2022 17:55:04 +0100 Subject: uaccess: generalize access_ok() 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 Acked-by: Mark Rutland [arm64, asm-generic] Acked-by: Geert Uytterhoeven Acked-by: Stafford Horne Acked-by: Dinh Nguyen Signed-off-by: Arnd Bergmann --- arch/um/include/asm/uaccess.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'arch/um/include') diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h index 1ecfc96bcc50..7d9d60e41e4e 100644 --- a/arch/um/include/asm/uaccess.h +++ b/arch/um/include/asm/uaccess.h @@ -25,7 +25,7 @@ extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n); extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n); extern unsigned long __clear_user(void __user *mem, unsigned long len); -static inline int __access_ok(unsigned long addr, unsigned long size); +static inline int __access_ok(const void __user *ptr, unsigned long size); /* Teach asm-generic/uaccess.h that we have C functions for these. */ #define __access_ok __access_ok @@ -36,8 +36,9 @@ static inline int __access_ok(unsigned long addr, unsigned long size); #include -static inline int __access_ok(unsigned long addr, unsigned long size) +static inline int __access_ok(const void __user *ptr, unsigned long size) { + unsigned long addr = (unsigned long)ptr; return __addr_range_nowrap(addr, size) && (__under_task_size(addr, size) || __access_ok_vsyscall(addr, size)); -- cgit v1.2.3