Whenever a buggy NAPI driver returns more than its budget,
we emit a stack trace that is of no use, since it does not
tell which driver is buggy.
Instead, emit a message giving the function name, and a
descriptive message.
Signed-off-by: Eric Dumazet <email address hidden>
Signed-off-by: David S. Miller <email address hidden>
(cherry picked from commit 427d5838e99632e9218eae752009c873cade89ac)
Signed-off-by: Po-Hsu Lin <email address hidden>
Acked-by: Stefan Bader <email address hidden>
Acked-by: Kleber Sacilotto de Souza <email address hidden>
Signed-off-by: Ian May <email address hidden>
RTAS may be used to read arbritary memory, which we do not want to allow when
Secure Boot is used. It is restricted to only some allowed operations, which
are the ones that are used by distributed tools.
CVE-2020-27777
Signed-off-by: Thadeu Lima de Souza Cascardo <email address hidden>
Acked-by: Kleber Sacilotto de Souza <email address hidden>
Acked-by: Stefan Bader <email address hidden>
Signed-off-by: Ian May <email address hidden>
c01eae0...
by
Andrew Donnellan <email address hidden>
powerpc/rtas: Restrict RTAS requests from userspace
A number of userspace utilities depend on making calls to RTAS to retrieve
information and update various things.
The existing API through which we expose RTAS to userspace exposes more
RTAS functionality than we actually need, through the sys_rtas syscall,
which allows root (or anyone with CAP_SYS_ADMIN) to make any RTAS call they
want with arbitrary arguments.
Many RTAS calls take the address of a buffer as an argument, and it's up to
the caller to specify the physical address of the buffer as an argument. We
allocate a buffer (the "RMO buffer") in the Real Memory Area that RTAS can
access, and then expose the physical address and size of this buffer in
/proc/powerpc/rtas/rmo_buffer. Userspace is expected to read this address,
poke at the buffer using /dev/mem, and pass an address in the RMO buffer to
the RTAS call.
However, there's nothing stopping the caller from specifying whatever
address they want in the RTAS call, and it's easy to construct a series of
RTAS calls that can overwrite arbitrary bytes (even without /dev/mem
access).
Additionally, there are some RTAS calls that do potentially dangerous
things and for which there are no legitimate userspace use cases.
In the past, this would not have been a particularly big deal as it was
assumed that root could modify all system state freely, but with Secure
Boot and lockdown we need to care about this.
We can't fundamentally change the ABI at this point, however we can address
this by implementing a filter that checks RTAS calls against a list
of permitted calls and forces the caller to use addresses within the RMO
buffer.
The list is based off the list of calls that are used by the librtas
userspace library, and has been tested with a number of existing userspace
RTAS utilities. For compatibility with any applications we are not aware of
that require other calls, the filter can be turned off at build time.
Cc: <email address hidden>
Reported-by: Daniel Axtens <email address hidden>
Signed-off-by: Andrew Donnellan <email address hidden>
Signed-off-by: Michael Ellerman <email address hidden>
Link: https://<email address hidden>
(backported from commit bd59380c5ba4147dcbaad3e582b55ccfd120b764)
CVE-2020-27777
Signed-off-by: Thadeu Lima de Souza Cascardo <email address hidden>
Acked-by: Kleber Sacilotto de Souza <email address hidden>
Acked-by: Stefan Bader <email address hidden>
Signed-off-by: Ian May <email address hidden>
This happens because at btrfs_read_qgroup_config() we can call
qgroup_rescan_init() while holding a read lock on a quota btree leaf,
acquired by the previous call to btrfs_search_slot_for_read(), and
qgroup_rescan_init() acquires the mutex qgroup_rescan_lock.
A qgroup rescan worker does the opposite: it acquires the mutex
qgroup_rescan_lock, at btrfs_qgroup_rescan_worker(), and then tries to
update the qgroup status item in the quota btree through the call to
update_qgroup_status_item(). This inversion of locking order
between the qgroup_rescan_lock mutex and quota btree locks causes the
splat.
Fix this simply by releasing and freeing the path before calling
qgroup_rescan_init() at btrfs_read_qgroup_config().
CC: <email address hidden> # 4.4+
Signed-off-by: Filipe Manana <email address hidden>
Reviewed-by: David Sterba <email address hidden>
Signed-off-by: David Sterba <email address hidden>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <email address hidden>
Signed-off-by: Greg Kroah-Hartman <email address hidden>
Signed-off-by: Kamal Mostafa <email address hidden>
Signed-off-by: Ian May <email address hidden>
