diff options
Diffstat (limited to 'lib/strnlen_user.c')
| -rw-r--r-- | lib/strnlen_user.c | 33 |
1 files changed, 14 insertions, 19 deletions
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c index 7f2db3fe311f..feeb935a2299 100644 --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -2,16 +2,11 @@ #include <linux/kernel.h> #include <linux/export.h> #include <linux/uaccess.h> +#include <linux/mm.h> +#include <linux/bitops.h> #include <asm/word-at-a-time.h> -/* Set bits in the first 'n' bytes when loaded from memory */ -#ifdef __LITTLE_ENDIAN -# define aligned_byte_mask(n) ((1ul << 8*(n))-1) -#else -# define aligned_byte_mask(n) (~0xfful << (BITS_PER_LONG - 8 - 8*(n))) -#endif - /* * Do a strnlen, return length of string *with* final '\0'. * 'count' is the user-supplied count, while 'max' is the @@ -25,20 +20,13 @@ * if it fits in a aligned 'long'. The caller needs to check * the return value against "> max". */ -static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max) +static __always_inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max) { const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; unsigned long align, res = 0; unsigned long c; /* - * Truncate 'max' to the user-specified limit, so that - * we only have one limit we need to check in the loop - */ - if (max > count) - max = count; - - /* * Do everything aligned. But that means that we * need to also expand the maximum.. */ @@ -108,15 +96,22 @@ long strnlen_user(const char __user *str, long count) if (unlikely(count <= 0)) return 0; - max_addr = user_addr_max(); - src_addr = (unsigned long)str; + max_addr = TASK_SIZE_MAX; + src_addr = (unsigned long)untagged_addr(str); if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; long retval; - if (user_access_begin(str, max)) { + /* + * Truncate 'max' to the user-specified limit, so that + * we only have one limit we need to check in the loop + */ + if (max > count) + max = count; + + if (user_read_access_begin(str, max)) { retval = do_strnlen_user(str, count, max); - user_access_end(); + user_read_access_end(); return retval; } } |