linux-kernel - Re: PROBLEM: fanotify

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Message-ID: <20201103211747.GA3688@gmail.com>
Date:   Tue, 3 Nov 2020 22:17:47 +0100
From:   Paweł Jasiak <pawel@...iak.xyz>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Brian Gerst <brgerst@...il.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: PROBLEM: fanotify_mark EFAULT on x86

I have written small patch that fixes problem for me and doesn't break
x86_64.

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 3e01d8f2ab90..cf0b97309975 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1285,12 +1285,27 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	return ret;
 }
 
+#if defined(CONFIG_X86) && !defined(CONFIG_64BIT)
+SYSCALL_DEFINE6(fanotify_mark,
+			int, fanotify_fd, unsigned int, flags, __u32, mask0,
+			__u32, mask1, int, dfd, const char  __user *, pathname)
+{
+	return do_fanotify_mark(fanotify_fd, flags,
+#ifdef __BIG_ENDIAN
+				((__u64)mask0 << 32) | mask1,
+#else
+				((__u64)mask1 << 32) | mask0,
+#endif
+				 dfd, pathname);
+}
+#else
 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
 			      __u64, mask, int, dfd,
 			      const char  __user *, pathname)
 {
 	return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
 }
+#endif
 
 #ifdef CONFIG_COMPAT
 COMPAT_SYSCALL_DEFINE6(fanotify_mark,


-- 

Paweł Jasiak