What happens is that a write to /dev/sg is given a request with non-zero
->iovec_count combined with zero ->dxfer_len. Or with ->dxferp pointing
to an array full of empty iovecs.
Having write permission to /dev/sg shouldn't be equivalent to the
ability to trigger BUG_ON() while holding spinlocks...
Found by Dmitry Vyukov and syzkaller.
[ The BUG_ON() got changed to a WARN_ON_ONCE(), but this fixes the
underlying issue. - Linus ]
Signed-off-by: Al Viro <[email protected]>
Reported-by: Dmitry Vyukov <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
In all the years it's been in the tree it had never been used by
anything - it would instantly trigger BUG_ON() in fs/fcntl.c due to
bogus band argument (ie. POLLIN not POLL_IN) passed to kill_fasync().
Since nobody had ever used it in ten years, let's just rip it out and be
done with that.
Signed-off-by: Al Viro <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
The logics in pipe_advance() used to release all buffers past the new
position failed in cases when the number of buffers to release was equal
to pipe->buffers. If that happened, none of them had been released,
leaving pipe full. Worse, it was trivial to trigger and we end up with
pipe full of uninitialized pages. IOW, it's an infoleak.
Cc: [email protected] # v4.9
Reported-by: "Alan J. Wylie" <[email protected]>
Tested-by: "Alan J. Wylie" <[email protected]>
Signed-off-by: Al Viro <[email protected]>
In all but one case, the last two arguments are NULL and 0 resp.;
almost everyone just wants to switch nameidata to non-RCU mode.
The only exception is lookup_fast(), where we have a child dentry
we want to legitimize as well. Split these two cases.
Signed-off-by: Al Viro <[email protected]>
Both damn things interpret userland pointers embedded into the payload;
worse, they are actually traversing those. Leaving aside the bad
API design, this is very much _not_ safe to call with KERNEL_DS.
Bail out early if that happens.
Cc: [email protected]
Signed-off-by: Al Viro <[email protected]>
Problem similar to ones dealt with in "fold checks into iterate_and_advance()"
and followups, except that in this case we really want to do nothing when
asked for zero-length operation - unlike zero-length iterate_and_advance(),
zero-length iterate_all_kinds() has no side effects, and callers are simpler
that way.
That got exposed when copy_from_iter_full() had been used by tipc, which
builds an msghdr with zero payload and (now) feeds it to a primitive
based on iterate_all_kinds() instead of iterate_and_advance().
Reported-by: Jon Maloy <[email protected]>
Tested-by: Jon Maloy <[email protected]>
Signed-off-by: Al Viro <[email protected]>
... and fix the minor buglet in compat io_submit() - native one
kills ioctx as cleanup when put_user() fails. Get rid of
bogus compat_... in !CONFIG_AIO case, while we are at it - they
should simply fail with ENOSYS, same as for native counterparts.
Signed-off-by: Al Viro <[email protected]>
Make sure that clone_mnt() never returns a mount with MNT_SHARED in
flags, but without a valid ->mnt_group_id. That allows to demystify
do_make_slave() quite a bit, among other things.
Signed-off-by: Al Viro <[email protected]>
FWIW, there's a bit of abuse of struct kstat in overlayfs object
creation paths - for one thing, it ends up with a very small subset
of struct kstat (mode + rdev), for another it also needs link in
case of symlinks and ends up passing it separately.
IMO it would be better to introduce a separate object for that.
In principle, we might even lift that thing into general API and switch
->mkdir()/->mknod()/->symlink() to identical calling conventions. Hell
knows, perhaps ->create() as well...
Signed-off-by: Miklos Szeredi <[email protected]>
... and don't zero anything on short copy; just unlock
and return 0 if that has happened on non-uptodate page.
Signed-off-by: Al Viro <[email protected]>
If we had a short copy into an uptodate page, there's no reason
whatsoever to zero anything; OTOH, if that page had _not_ been
uptodate, we must have been trying to overwrite it completely
and got a short copy. In that case, overwriting the end with
zeroes, marking uptodate and sending to server is just plain
wrong. Just unlock, keep it non-uptodate and return 0.
Signed-off-by: Al Viro <[email protected]>
a) the page is uptodate - ->write_begin() would either fail (in which
case we don't reach ->write_end()), or unstuff the inode, or find the
page already uptodate, or do a successful call of stuffed_readpage(),
which would've made it uptodate
b) zeroing the tail in pagecache is wrong. kill -9 at the right time
while writing unmodified file contents to the same file should _not_
leave us in a situation when read() from the file will be reporting
it full of zeroes. Especially since that effect will be transient -
at some later point the page will be evicted and then we'll be back
to the real file contents.
Signed-off-by: Al Viro <[email protected]>
don't zero on short copies; if the page was uptodate it's just plain
wrong, and if it wasn't we'll be better off just returning 0 and
buggering off.
Signed-off-by: Al Viro <[email protected]>
What matters when deciding if we should make a page uptodate is
not how much we _wanted_ to copy, but how much we actually have
copied. As it is, on architectures that do not zero tail on
short copy we can leave uninitialized data in page marked uptodate.
Cc: [email protected]
Signed-off-by: Al Viro <[email protected]>
All callers are followed by the same boilerplate - "if it has returned
0, update nd->path/inode/seq - we are not following a symlink here".
Pull it into the function itself, renaming it into step_into().
Rename WALK_GET to WALK_FOLLOW, while we are at it - more descriptive
name.
Signed-off-by: Al Viro <[email protected]>
... turning the condition for put_link() in walk_component() into
"WALK_MORE not passed and depth is non-zero". Again, makes for
simpler arguments.
Signed-off-by: Al Viro <[email protected]>
copy_from_iter_full(), copy_from_iter_full_nocache() and
csum_and_copy_from_iter_full() - counterparts of copy_from_iter()
et.al., advancing iterator only in case of successful full copy
and returning whether it had been successful or not.
Convert some obvious users. *NOTE* - do not blindly assume that
something is a good candidate for those unless you are sure that
not advancing iov_iter in failure case is the right thing in
this case. Anything that does short read/short write kind of
stuff (or is in a loop, etc.) is unlikely to be a good one.
Signed-off-by: Al Viro <[email protected]>
Botched calculation of number of pages. As the result,
we were dropping pieces when doing splice to pipe from
e.g. 9p.
Reported-by: Alexei Starovoitov <[email protected]>
Tested-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Al Viro <[email protected]>
i_size check is a leftover from the horrors that used to play with
the page cache in that function. With the switch to ->read_iter(),
it's neither needed nor correct - for gfs2 it ends up being buggy,
since i_size is not guaranteed to be correct until later (inside
->read_iter()).
Spotted-by: Abhi Das <[email protected]>
Signed-off-by: Al Viro <[email protected]>
it actually worked only when requested area ended on the page boundary...
Reported-by: Marco Grassi <[email protected]>
Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
looking for duplicate ->iov_base makes sense only for
iovec-backed iterators; for kvec-backed ones it's pointless,
for bvec-backed ones it's pointless and broken on 32bit (we
walk through an array of struct bio_vec accessing them as if
they were struct iovec; works by accident on 64bit, but on
32bit it'll blow up) and for pipe-backed ones it's pointless
and ends up oopsing.
Signed-off-by: Al Viro <[email protected]>
by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case. Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().
Signed-off-by: Al Viro <[email protected]>
more victims of indirect include chains - au1200fb
lasat/picvue_proc and watchdog/ath79_wdt
... as well as tb0219, spotted by Sudip Mukherjee
Signed-off-by: Al Viro <[email protected]>
we only use iov_iter_get_pages_alloc() and iov_iter_advance() -
pages are filled by kernel_readv() via a kvec array (as we used
to do all along), so iov_iter here is used only as a way of
arranging for those pages to be in pipe.
Signed-off-by: Al Viro <[email protected]>
iov_iter variant for passing data into pipe. copy_to_iter()
copies data into page(s) it has allocated and stuffs them into
the pipe; copy_page_to_iter() stuffs there a reference to the
page given to it. Both will try to coalesce if possible.
iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages()
and friends will do as copy_to_iter() would have and return the
pages where the data would've been copied. iov_iter_advance()
will truncate everything past the spot it has advanced to.
New primitive: iov_iter_pipe(), used for initializing those.
pipe should be locked all along.
Running out of space acts as fault would for iovec-backed ones;
in other words, giving it to ->read_iter() may result in short
read if the pipe overflows, or -EFAULT if it happens with nothing
copied there.
In other words, ->read_iter() on those acts pretty much like
->splice_read(). Moreover, all generic_file_splice_read() users,
as well as many other ->splice_read() instances can be switched
to that scheme - that'll happen in the next commit.
Signed-off-by: Al Viro <[email protected]>
since pipe_lock is the outermost now, we don't need to drop/regain
socket locks around the call of splice_to_pipe() from skb_splice_bits(),
which kills the need to have a socket-specific callback; we can just
call splice_to_pipe() and be done with that.
Signed-off-by: Al Viro <[email protected]>
single-buffer analogue of splice_to_pipe(); vmsplice_to_pipe() switched
to that, leaving splice_to_pipe() only for ->splice_read() instances
(and that only until they are converted as well).
Signed-off-by: Al Viro <[email protected]>
* splice_to_pipe() stops at pipe overflow and does *not* take pipe_lock
* ->splice_read() instances do the same
* vmsplice_to_pipe() and do_splice() (ultimate callers of splice_to_pipe())
arrange for waiting, looping, etc. themselves.
That should make pipe_lock the outermost one.
Unfortunately, existing rules for the amount passed by vmsplice_to_pipe()
and do_splice() are quite ugly _and_ userland code can be easily broken
by changing those. It's not even "no more than the maximal capacity of
this pipe" - it's "once we'd fed pipe->nr_buffers pages into the pipe,
leave instead of waiting".
Considering how poorly these rules are documented, let's try "wait for some
space to appear, unless given SPLICE_F_NONBLOCK, then push into pipe
and if we run into overflow, we are done".
Signed-off-by: Al Viro <[email protected]>
Make local filesystems treat a fault as shortened IO,
returning -EFAULT only if nothing had been transferred.
That's how everything else (NFS, FUSE, ceph, Lustre)
behaves.
Signed-off-by: Al Viro <[email protected]>
Al Viro