Messages in this thread Patch in this message | | | Date | Thu, 30 Apr 2020 20:07:33 -0500 | From | Josh Poimboeuf <> | Subject | Re: Remaining randconfig objtool warnings, linux-next-20200428 |
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On Thu, Apr 30, 2020 at 04:05:07PM +0200, Arnd Bergmann wrote: > lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x133: call to do_strncpy_from_user() with UACCESS enabled > lib/strnlen_user.o: warning: objtool: strnlen_user()+0x122: call to do_strnlen_user() with UACCESS enabled
Does this fix it?
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index 706020b06617..cb3ae7a093c3 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -30,6 +30,9 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; unsigned long res = 0; + if (!user_access_begin(src, max)) + return -EFAULT; + if (IS_UNALIGNED(src, dst)) goto byte_at_a_time; @@ -43,7 +46,8 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, if (has_zero(c, &data, &constants)) { data = prep_zero_mask(c, data, &constants); data = create_zero_mask(data); - return res + find_zero(data); + res += find_zero(data); + goto done; } res += sizeof(unsigned long); max -= sizeof(unsigned long); @@ -56,7 +60,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, unsafe_get_user(c,src+res, efault); dst[res] = c; if (!c) - return res; + goto done; res++; max--; } @@ -65,14 +69,20 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, * Uhhuh. We hit 'max'. But was that the user-specified maximum * too? If so, that's ok - we got as much as the user asked for. */ - if (res >= count) - return res; + if (res < count) { + /* + * Nope: we hit the address space limit, and we still had more + * characters the caller would have wanted. That's an EFAULT. + */ + goto efault; + } + +done: + user_access_end(); + return res; - /* - * Nope: we hit the address space limit, and we still had more - * characters the caller would have wanted. That's an EFAULT. - */ efault: + user_access_end(); return -EFAULT; } @@ -105,7 +115,6 @@ long strncpy_from_user(char *dst, const char __user *src, long count) src_addr = (unsigned long)untagged_addr(src); if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; - long retval; /* * Truncate 'max' to the user-specified limit, so that @@ -116,11 +125,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count) kasan_check_write(dst, count); check_object_size(dst, count, false); - if (user_access_begin(src, max)) { - retval = do_strncpy_from_user(dst, src, count, max); - user_access_end(); - return retval; - } + return do_strncpy_from_user(dst, src, count, max); } return -EFAULT; } diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c index 41670d4a5816..f1e9e447bef1 100644 --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -26,6 +26,9 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long align, res = 0; unsigned long c; + if (!user_access_begin(src, max)) + return 0; + /* * Do everything aligned. But that means that we * need to also expand the maximum.. @@ -39,10 +42,12 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count, for (;;) { unsigned long data; + if (has_zero(c, &data, &constants)) { data = prep_zero_mask(c, data, &constants); data = create_zero_mask(data); - return res + find_zero(data) + 1 - align; + res += find_zero(data) + 1 - align; + goto done; } res += sizeof(unsigned long); /* We already handled 'unsigned long' bytes. Did we do it all ? */ @@ -58,13 +63,21 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count, * too? If so, return the marker for "too long". */ if (res >= count) - return count+1; + res = count + 1; + else { + /* + * Nope: we hit the address space limit, and we still had more + * characters the caller would have wanted. That's 0. + */ + goto efault; + } + +done: + user_access_end(); + return res; - /* - * Nope: we hit the address space limit, and we still had more - * characters the caller would have wanted. That's 0. - */ efault: + user_access_end(); return 0; } @@ -100,7 +113,6 @@ long strnlen_user(const char __user *str, long count) src_addr = (unsigned long)untagged_addr(str); if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; - long retval; /* * Truncate 'max' to the user-specified limit, so that @@ -109,11 +121,7 @@ long strnlen_user(const char __user *str, long count) if (max > count) max = count; - if (user_access_begin(str, max)) { - retval = do_strnlen_user(str, count, max); - user_access_end(); - return retval; - } + return do_strnlen_user(str, count, max); } return 0; }
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