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authorJan Beulich <JBeulich@suse.com>2013-10-21 12:43:57 +0400
committerIngo Molnar <mingo@kernel.org>2013-10-26 14:27:36 +0400
commit3df7b41aa5e7797f391d0a41f8b0dce1fe366a09 (patch)
treef79334f0230b5728f1b541e1ef500373c0f764a6 /arch/x86/include/asm/uaccess_32.h
parent88829dfe4b6ea0c1c24d415668b3bfa78e5a5b16 (diff)
downloadlinux-3df7b41aa5e7797f391d0a41f8b0dce1fe366a09.tar.xz
x86: Unify copy_from_user() size checking
Commits 4a3127693001c61a21d1ce680db6340623f52e93 ("x86: Turn the copy_from_user check into an (optional) compile time warning") and 63312b6a6faae3f2e5577f2b001e3b504f10a2aa ("x86: Add a Kconfig option to turn the copy_from_user warnings into errors") touched only the 32-bit variant of copy_from_user(), whereas the original commit 9f0cf4adb6aa0bfccf675c938124e68f7f06349d ("x86: Use __builtin_object_size() to validate the buffer size for copy_from_user()") also added the same code to the 64-bit one. Further the earlier conversion from an inline WARN() to the call to copy_from_user_overflow() went a little too far: When the number of bytes to be copied is not a constant (e.g. [looking at 3.11] in drivers/net/tun.c:__tun_chr_ioctl() or drivers/pci/pcie/aer/aer_inject.c:aer_inject_write()), the compiler will always have to keep the funtion call, and hence there will always be a warning. By using __builtin_constant_p() we can avoid this. And then this slightly extends the effect of CONFIG_DEBUG_STRICT_USER_COPY_CHECKS in that apart from converting warnings to errors in the constant size case, it retains the (possibly wrong) warnings in the non-constant size case, such that if someone is prepared to get a few false positives, (s)he'll be able to recover the current behavior (except that these diagnostics now will never be converted to errors). Since the 32-bit variant (intentionally) didn't call might_fault(), the unification results in this being called twice now. Adding a suitable #ifdef would be the alternative if that's a problem. I'd like to point out though that with __compiletime_object_size() being restricted to gcc before 4.6, the whole construct is going to become more and more pointless going forward. I would question however that commit 2fb0815c9ee6b9ac50e15dd8360ec76d9fa46a2 ("gcc4: disable __compiletime_object_size for GCC 4.6+") was really necessary, and instead this should have been dealt with as is done here from the beginning. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/5265056D02000078000FC4F3@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/uaccess_32.h')
-rw-r--r--arch/x86/include/asm/uaccess_32.h26
1 files changed, 0 insertions, 26 deletions
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 7f760a9f1f61..c348c87cefc8 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -186,31 +186,5 @@ __copy_from_user_inatomic_nocache(void *to, const void __user *from,
unsigned long __must_check copy_to_user(void __user *to,
const void *from, unsigned long n);
-unsigned long __must_check _copy_from_user(void *to,
- const void __user *from,
- unsigned long n);
-
-
-extern void copy_from_user_overflow(void)
-#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
- __compiletime_error("copy_from_user() buffer size is not provably correct")
-#else
- __compiletime_warning("copy_from_user() buffer size is not provably correct")
-#endif
-;
-
-static 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 == -1 || sz >= n))
- n = _copy_from_user(to, from, n);
- else
- copy_from_user_overflow();
-
- return n;
-}
#endif /* _ASM_X86_UACCESS_32_H */