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From: Matthew Wilcox <willy@infradead.org>
To: "Paweł Jasiak" <pawel@jasiak.xyz>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	jack@suse.cz
Subject: Re: PROBLEM: fanotify_mark EFAULT on x86
Date: Sun, 1 Nov 2020 21:38:45 +0000	[thread overview]
Message-ID: <20201101213845.GH27442@casper.infradead.org> (raw)
In-Reply-To: <20201101212738.GA16924@gmail.com>

On Sun, Nov 01, 2020 at 10:27:38PM +0100, Paweł Jasiak wrote:
> I am trying to run examples from man fanotify.7 but fanotify_mark always
> fail with errno = EFAULT.
> 
> fanotify_mark declaration is
> 
> SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
> 			      __u64, mask, int, dfd,
> 			      const char  __user *, pathname)

Don't worry about that.  You aren't calling the SYSCALL, you're calling
glibc and glibc is turning it into a syscall.

extern int fanotify_mark (int __fanotify_fd, unsigned int __flags,
                          uint64_t __mask, int __dfd, const char *__pathname)

> When 
> 
> fanotify_mark(4, FAN_MARK_ADD | FAN_MARK_ONLYDIR,
>               FAN_CREATE | FAN_ONDIR, AT_FDCWD, 0xdeadc0de)

The last argument is supposed to be a pointer to a string.  I'm guessing
there's no string at 0xdeadc0de.


  reply	other threads:[~2020-11-01 21:47 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-01 21:27 PROBLEM: fanotify_mark EFAULT on x86 Paweł Jasiak
2020-11-01 21:38 ` Matthew Wilcox [this message]
2020-11-01 22:27   ` Paweł Jasiak
2020-11-02 12:26 ` Jan Kara
2020-11-02 17:16   ` Paweł Jasiak
2020-11-03 21:17   ` Paweł Jasiak
2020-11-04 10:14     ` Jan Kara
2020-11-23 16:46     ` Jan Kara
2020-11-23 22:46       ` Paweł Jasiak
2020-11-24  8:45         ` Borislav Petkov
2020-11-24 10:20           ` Jan Kara
2020-11-24 10:28             ` Borislav Petkov
2020-11-26 10:48               ` Jan Kara
2020-11-26 10:52                 ` Borislav Petkov
2020-11-25 19:31             ` Naresh Kamboju
2020-11-26 10:48               ` Jan Kara
2020-11-23 23:07       ` [PATCH] fanotify: Fix fanotify_mark() on 32-bit archs kernel test robot

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