fe87309...
by
Vlastimil Babka <email address hidden>
mm: try_to_unmap_cluster() should lock_page() before mlocking
A BUG_ON(!PageLocked) was triggered in mlock_vma_page() by Sasha Levin
fuzzing with trinity. The call site try_to_unmap_cluster() does not lock
the pages other than its check_page parameter (which is already locked).
The BUG_ON in mlock_vma_page() is not documented and its purpose is
somewhat unclear, but apparently it serializes against page migration,
which could otherwise fail to transfer the PG_mlocked flag. This would
not be fatal, as the page would be eventually encountered again, but
NR_MLOCK accounting would become distorted nevertheless. This patch adds
a comment to the BUG_ON in mlock_vma_page() and munlock_vma_page() to that
effect.
The call site try_to_unmap_cluster() is fixed so that for page !=
check_page, trylock_page() is attempted (to avoid possible deadlocks as we
already have check_page locked) and mlock_vma_page() is performed only
upon success. If the page lock cannot be obtained, the page is left
without PG_mlocked, which is again not a problem in the whole unevictable
memory design.
Signed-off-by: Vlastimil Babka <email address hidden>
Signed-off-by: Bob Liu <email address hidden>
Reported-by: Sasha Levin <email address hidden>
Cc: Wanpeng Li <email address hidden>
Cc: Michel Lespinasse <email address hidden>
Cc: KOSAKI Motohiro <email address hidden>
Acked-by: Rik van Riel <email address hidden>
Cc: David Rientjes <email address hidden>
Cc: Mel Gorman <email address hidden>
Cc: Hugh Dickins <email address hidden>
Cc: Joonsoo Kim <email address hidden>
Cc: <email address hidden>
Signed-off-by: Andrew Morton <email address hidden>
Signed-off-by: Linus Torvalds <email address hidden>
(back ported from commit 57e68e9cd65b4b8eb4045a1e0d0746458502554c)
CVE-2014-3122
BugLink: http://bugs.launchpad.net/bugs/1316268
Signed-off-by: Luis Henriques <email address hidden>
Acked-by: Andy Whitcroft <email address hidden>
Signed-off-by: Tim Gardner <email address hidden>
Do not leak kernel-only floppy_raw_cmd structure members to userspace.
This includes the linked-list pointer and the pointer to the allocated
DMA space.
Signed-off-by: Matthew Daley <email address hidden>
Signed-off-by: Linus Torvalds <email address hidden>
(cherry picked from commit 2145e15e0557a01b9195d1c7199a1b92cb9be81f)
Acked-by: Andy Whitcroft <email address hidden>
Signed-off-by: Kamal Mostafa <email address hidden>
c677329...
by
Matthew Daley <email address hidden>
floppy: ignore kernel-only members in FDRAWCMD ioctl input
Always clear out these floppy_raw_cmd struct members after copying the
entire structure from userspace so that the in-kernel version is always
valid and never left in an interdeterminate state.
Signed-off-by: Matthew Daley <email address hidden>
Signed-off-by: Linus Torvalds <email address hidden>
(cherry picked from commit ef87dbe7614341c2e7bfe8d32fcb7028cc97442c)
Acked-by: Andy Whitcroft <email address hidden>
Signed-off-by: Kamal Mostafa <email address hidden>
The tty atomic_write_lock does not provide an exclusion guarantee for
the tty driver if the termios settings are LECHO & !OPOST. And since
it is unexpected and not allowed to call TTY buffer helpers like
tty_insert_flip_string concurrently, this may lead to crashes when
concurrect writers call pty_write. In that case the following two
writers:
* the ECHOing from a workqueue and
* pty_write from the process
race and can overflow the corresponding TTY buffer like follows.
If we look into tty_insert_flip_string_fixed_flag, there is:
int space = __tty_buffer_request_room(port, goal, flags);
struct tty_buffer *tb = port->buf.tail;
...
memcpy(char_buf_ptr(tb, tb->used), chars, space);
...
tb->used += space;
so the race of the two can result in something like this:
A B
__tty_buffer_request_room __tty_buffer_request_room
memcpy(buf(tb->used), ...)
tb->used += space; memcpy(buf(tb->used), ...) ->BOOM
B's memcpy is past the tty_buffer due to the previous A's tb->used
increment.
Since the N_TTY line discipline input processing can output
concurrently with a tty write, obtain the N_TTY ldisc output_lock to
serialize echo output with normal tty writes. This ensures the tty
buffer helper tty_insert_flip_string is not called concurrently and
everything is fine.
Note that this is nicely reproducible by an ordinary user using
forkpty and some setup around that (raw termios + ECHO). And it is
present in kernels at least after commit
d945cb9cce20ac7143c2de8d88b187f62db99bdc (pty: Rework the pty layer to
use the normal buffering logic) in 2.6.31-rc3.
js: add more info to the commit log
js: switch to bool
js: lock unconditionally
js: lock only the tty->ops->write call
