Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds <torvalds@linux-foundation.org>]

On Sun, 8 Jul 2007, Ulrich Drepper wrote:
> 
> But the real permissions tests are performed in notify_change.  I think
> all this is consistent with how, for instance, fchmod works.  The
> additional tests in fchmod which aren't here (IS_RDONLY and IS_APPEND)
> would also apply to the case where a file name is given.  So, either the
> code was inconsistent already are these tests are really not needed.

No.

notify_change() does *not* do permission checks for 
ATTR_CTIME/MTIME/ATIME.

It does them for the "xxx_SET" attributes, but MTIME/ATIME is expected to 
change when other things change, so notify_change() expects that those 
_other_ changes have been validated from a security standpoint!

utimes() is special.

		Linus
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