From: Andrew Morton Date: Thu, 7 Dec 2006 04:36:40 +0000 (-0800) Subject: [PATCH] probe_kernel_address() needs to do set_fs() X-Git-Tag: v2.6.20-rc1~145^2^2~193 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=20aa7b21b1cbd1aa3fbf5fc14da5f7484a61a824;p=linux-2.6 [PATCH] probe_kernel_address() needs to do set_fs() probe_kernel_address() purports to be generic, only it forgot to select KERNEL_DS, so it presently won't work right on all architectures. Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 67918c2233..76c3fe3251 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -65,14 +65,22 @@ static inline unsigned long __copy_from_user_nocache(void *to, * do_page_fault() doesn't attempt to take mmap_sem. This makes * probe_kernel_address() suitable for use within regions where the caller * already holds mmap_sem, or other locks which nest inside mmap_sem. + * This must be a macro because __get_user() needs to know the types of the + * args. + * + * We don't include enough header files to be able to do the set_fs(). We + * require that the probe_kernel_address() caller will do that. */ #define probe_kernel_address(addr, retval) \ ({ \ long ret; \ + mm_segment_t old_fs = get_fs(); \ \ + set_fs(KERNEL_DS); \ pagefault_disable(); \ ret = __get_user(retval, addr); \ pagefault_enable(); \ + set_fs(old_fs); \ ret; \ })