lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Thu, 28 Mar 2013 10:06:35 -0400
From:	Theodore Ts'o <>
To:	Zheng Liu <>,
	Al Viro <>
Subject: Re: [PATCH] ext4: take i_mutex in ext4_symlink to eliminate a
 warning from ext4_truncate

I looked more closely at the assumption that ext4_write_begin() holds
i_mutex.  This is guaranteed by Documentation/filesystems/Locking,
which notes that write_begin() and write_end() functions hold i_mutex:

			PageLocked(page)	i_mutex
write_begin:		locks the page		yes
write_end:		yes, unlocks		yes

So the bug is that ext4_symlink() calls __page_symlink();
__page_symlink() calls pagecache_write_begin() which calls
write_begin(), without taking i_mutex.

So we can fix this by taking i_mutex in ext4_symlink(), but I think it
would be better to take the i_mutex in __page_symlink(), since it
would then address a violation of the locking rules for all file

Al, do you agree?

					- Ted
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists