Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] copy_{to,from}_user(): fix compile-time sanity checks with gcc -Og | Date | Fri, 2 Nov 2018 16:56:58 +0100 |
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When CONFIG_CC_OPTIMIZE_FOR_DEBUGGING is set, we get countless warnings like
In function 'check_copy_size', inlined from 'copy_from_user' at include/linux/uaccess.h:146:6, inlined from '__copy_siginfo_from_user' at kernel/signal.c:3032:6: include/linux/thread_info.h:147:4: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small
It seems that constant propagation doesn't work well enough to make this code reliable, so turn it off for that configuration.
Cc: Changbin Du<changbin.du@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/thread_info.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 8d8821b3689a..762f379bdf5d 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -138,6 +138,11 @@ static __always_inline bool check_copy_size(const void *addr, size_t bytes, bool is_source) { int sz = __compiletime_object_size(addr); + + /* constant propagation doesn't work well with -Og */ + if (IS_ENABLED(CONFIG_CC_OPTIMIZE_FOR_DEBUGGING)) + return true; + if (unlikely(sz >= 0 && sz < bytes)) { if (!__builtin_constant_p(bytes)) copy_overflow(sz, bytes); -- 2.18.0
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