linux-stable.git/arch/sparc/kernel, branch linux-4.4.y

sparc: avoid stringop-overread errors

2021-10-06T08:22:24+00:00

[ Upstream commit fc7c028dcdbfe981bca75d2a7b95f363eb691ef3 ]

The sparc mdesc code does pointer games with 'struct mdesc_hdr', but
didn't describe to the compiler how that header is then followed by the
data that the header describes.

As a result, gcc is now unhappy since it does stricter pointer range
tracking, and doesn't understand about how these things work.  This
results in various errors like:

    arch/sparc/kernel/mdesc.c: In function ‘mdesc_node_by_name’:
    arch/sparc/kernel/mdesc.c:647:22: error: ‘strcmp’ reading 1 or more bytes from a region of size 0 [-Werror=stringop-overread]
      647 |                 if (!strcmp(names + ep[ret].name_offset, name))
          |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

which are easily avoided by just describing 'struct mdesc_hdr' better,
and making the node_block() helper function look into that unsized
data[] that follows the header.

This makes the sparc64 build happy again at least for my cross-compiler
version (gcc version 11.2.1).

Link: https://lore.kernel.org/lkml/CAHk-=wi4NW3NC0xWykkw=6LnjQD6D_rtRtxY9g8gQAJXtQMi8A@mail.gmail.com/
Cc: Guenter Roeck 
Cc: David S. Miller 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

sparc64: remove mm_cpumask clearing to fix kthread_use_mm race

2020-11-10T09:22:13+00:00

[ Upstream commit bafb056ce27940c9994ea905336aa8f27b4f7275 ]

The de facto (and apparently uncommented) standard for using an mm had,
thanks to this code in sparc if nothing else, been that you must have a
reference on mm_users *and that reference must have been obtained with
mmget()*, i.e., from a thread with a reference to mm_users that had used
the mm.

The introduction of mmget_not_zero() in commit d2005e3f41d4
("userfaultfd: don't pin the user memory in userfaultfd_file_create()")
allowed mm_count holders to aoperate on user mappings asynchronously
from the actual threads using the mm, but they were not to load those
mappings into their TLB (i.e., walking vmas and page tables is okay,
kthread_use_mm() is not).

io_uring 2b188cc1bb857 ("Add io_uring IO interface") added code which
does a kthread_use_mm() from a mmget_not_zero() refcount.

The problem with this is code which previously assumed mm == current->mm
and mm->mm_users == 1 implies the mm will remain single-threaded at
least until this thread creates another mm_users reference, has now
broken.

arch/sparc/kernel/smp_64.c:

    if (atomic_read(&mm->mm_users) == 1) {
        cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
        goto local_flush_and_out;
    }

vs fs/io_uring.c

    if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) ||
                 !mmget_not_zero(ctx->sqo_mm)))
        return -EFAULT;
    kthread_use_mm(ctx->sqo_mm);

mmget_not_zero() could come in right after the mm_users == 1 test, then
kthread_use_mm() which sets its CPU in the mm_cpumask. That update could
be lost if cpumask_copy() occurs afterward.

I propose we fix this by allowing mmget_not_zero() to be a first-class
reference, and not have this obscure undocumented and unchecked
restriction.

The basic fix for sparc64 is to remove its mm_cpumask clearing code. The
optimisation could be effectively restored by sending IPIs to mm_cpumask
members and having them remove themselves from mm_cpumask. This is more
tricky so I leave it as an exercise for someone with a sparc64 SMP.
powerpc has a (currently similarly broken) example.

Signed-off-by: Nicholas Piggin 
Acked-by: David S. Miller 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200914045219.3736466-4-npiggin@gmail.com
Signed-off-by: Sasha Levin

fix a braino in "sparc32: fix register window handling in genregs32_[gs]et()"

2020-06-30T00:07:57+00:00

[ Upstream commit 9d964e1b82d8182184153b70174f445ea616f053 ]

lost npc in PTRACE_SETREGSET, breaking PTRACE_SETREGS as well

Fixes: cf51e129b968 "sparc32: fix register window handling in genregs32_[gs]et()"
Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin

sparc64: fix misuses of access_process_vm() in genregs32_[sg]et()

2020-06-30T00:07:56+00:00

[ Upstream commit 142cd25293f6a7ecbdff4fb0af17de6438d46433 ]

We do need access_process_vm() to access the target's reg_window.
However, access to caller's memory (storing the result in
genregs32_get(), fetching the new values in case of genregs32_set())
should be done by normal uaccess primitives.

Fixes: ad4f95764040 ([SPARC64]: Fix user accesses in regset code.)
Cc: stable@kernel.org
Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin

sparc32: fix register window handling in genregs32_[gs]et()

2020-06-20T08:23:24+00:00

commit cf51e129b96847f969bfb8af1ee1516a01a70b39 upstream.

It needs access_process_vm() if the traced process does not share
mm with the caller.  Solution is similar to what sparc64 does.
Note that genregs32_set() is only ever called with pos being 0
or 32 * sizeof(u32) (the latter - as part of PTRACE_SETREGS
handling).

Cc: stable@kernel.org
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

sparc: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD

2019-07-10T07:56:32+00:00

[ Upstream commit 56cd0aefa475079e9613085b14a0f05037518fed ]

The PERF_EVENT_IOC_PERIOD ioctl command can be used to change the
sample period of a running perf_event. Consequently, when calculating
the next event period, the new period will only be considered after the
previous one has overflowed.

This patch changes the calculation of the remaining event ticks so that
they are offset if the period has changed.

See commit 3581fe0ef37c ("ARM: 7556/1: perf: fix updated event period in
response to PERF_EVENT_IOC_PERIOD") for details.

Signed-off-by: Young Xiao <92siuyang@gmail.com>
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

sparc: Fix single-pcr perf event counter management.

2018-11-21T08:27:30+00:00

[ Upstream commit cfdc3170d214046b9509183fe9b9544dc644d40b ]

It is important to clear the hw->state value for non-stopped events
when they are added into the PMU.  Otherwise when the event is
scheduled out, we won't read the counter because HES_UPTODATE is still
set.  This breaks 'perf stat' and similar use cases, causing all the
events to show zero.

This worked for multi-pcr because we make explicit sparc_pmu_start()
calls in calculate_multiple_pcrs().  calculate_single_pcr() doesn't do
this because the idea there is to accumulate all of the counter
settings into the single pcr value.  So we have to add explicit
hw->state handling there.

Like x86, we use the PERF_HES_ARCH bit to track truly stopped events
so that we don't accidently start them on a reload.

Related to all of this, sparc_pmu_start() is missing a userpage update
so add it.

Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

sparc/pci: Refactor dev_archdata initialization into pci_init_dev_archdata

2018-11-10T15:41:37+00:00

[ Upstream commit 9a78d4fc28904785ffe4c2d361e25b251b479704 ]

The function pcibios_add_device() added by commit d0c31e020057
("sparc/PCI: Fix for panic while enabling SR-IOV") initializes
the dev_archdata by doing a memcpy from the PF. This has the
problem that it erroneously copies the OF device without
explicitly refcounting it.

As David Miller pointed out: "Generally speaking we don't
really support hot-plug for OF probed devices, but if we did
all of the device tree pointers have to be refcounted properly."

To fix this error, and also avoid code duplication, this patch
creates a new helper function, pci_init_dev_archdata(), that
initializes the fields in dev_archdata, and can be invoked
by callers after they have taken the needed refcounts

Signed-off-by: Sowmini Varadhan 
Tested-by: Babu Moger 
Reviewed-by: Khalid Aziz 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

sys: don't hold uts_sem while accessing userspace memory

2018-09-09T18:04:35+00:00

commit 42a0cc3478584d4d63f68f2f5af021ddbea771fa upstream.

Holding uts_sem as a writer while accessing userspace memory allows a
namespace admin to stall all processes that attempt to take uts_sem.
Instead, move data through stack buffers and don't access userspace memory
while uts_sem is held.

Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn 
Signed-off-by: Eric W. Biederman 
Signed-off-by: Greg Kroah-Hartman

sparc64: Fix build warnings with gcc 7.

2018-06-06T14:46:23+00:00

commit 0fde7ad71ee371ede73b3f326e58f9e8d102feb6 upstream.

arch/sparc/kernel/ds.c: In function ‘register_services’:
arch/sparc/kernel/ds.c:912:3: error: ‘strcpy’: writing at least 1 byte
into a region of size 0 overflows the destination

Reported-by: Anatoly Pugachev 
Signed-off-by: David S. Miller 
Cc: Guenter Roeck 
Signed-off-by: Greg Kroah-Hartman