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copy_{to,from}_user(): consolidate object size checks

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... and move them into thread_info.h, next to check_object_size()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-06-29 21:42:43 -04:00
parent 9c5f6908de
commit b0377fedb6
2 changed files with 29 additions and 26 deletions
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27
include/linux/thread_info.h
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@ -113,6 +113,33 @@ static inline void check_object_size(const void *ptr, unsigned long n,
{ }
#endif /* CONFIG_HARDENED_USERCOPY */
extern void __compiletime_error("copy source size is too small")
__bad_copy_from(void);
extern void __compiletime_error("copy destination size is too small")
__bad_copy_to(void);
static inline void copy_overflow(int size, unsigned long count)
{
WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
}
static __always_inline bool
check_copy_size(const void *addr, size_t bytes, bool is_source)
{
int sz = __compiletime_object_size(addr);
if (unlikely(sz >= 0 && sz < bytes)) {
if (!__builtin_constant_p(bytes))
copy_overflow(sz, bytes);
else if (is_source)
__bad_copy_from();
else
__bad_copy_to();
return false;
}
check_object_size(addr, bytes, is_source);
return true;
}
#ifndef arch_setup_new_exec
static inline void arch_setup_new_exec(void) { }
#endif

28
include/linux/uaccess.h
View file

@ -139,43 +139,19 @@ extern unsigned long
_copy_to_user(void __user *, const void *, unsigned long);
#endif
extern void __compiletime_error("usercopy buffer size is too small")
__bad_copy_user(void);
static inline void copy_user_overflow(int size, unsigned long count)
{
WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
}
static __always_inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
int sz = __compiletime_object_size(to);
if (likely(sz < 0 || sz >= n)) {
check_object_size(to, n, false);
if (likely(check_copy_size(to, n, false)))
n = _copy_from_user(to, from, n);
} else if (!__builtin_constant_p(n))
copy_user_overflow(sz, n);
else
__bad_copy_user();
return n;
}
static __always_inline unsigned long __must_check
copy_to_user(void __user *to, const void *from, unsigned long n)
{
int sz = __compiletime_object_size(from);
if (likely(sz < 0 || sz >= n)) {
check_object_size(from, n, true);
if (likely(check_copy_size(from, n, true)))
n = _copy_to_user(to, from, n);
} else if (!__builtin_constant_p(n))
copy_user_overflow(sz, n);
else
__bad_copy_user();
return n;
}
#ifdef CONFIG_COMPAT