linux-stable.git/kernel, branch v6.1.136

bpf: Fix deadlock between rcu_tasks_trace and event_mutex.

2025-05-02T05:47:01+00:00

[ Upstream commit 4580f4e0ebdf8dc8d506ae926b88510395a0c1d1 ]

Fix the following deadlock:
CPU A
_free_event()
  perf_kprobe_destroy()
    mutex_lock(&event_mutex)
      perf_trace_event_unreg()
        synchronize_rcu_tasks_trace()

There are several paths where _free_event() grabs event_mutex
and calls sync_rcu_tasks_trace. Above is one such case.

CPU B
bpf_prog_test_run_syscall()
  rcu_read_lock_trace()
    bpf_prog_run_pin_on_cpu()
      bpf_prog_load()
        bpf_tracing_func_proto()
          trace_set_clr_event()
            mutex_lock(&event_mutex)

Delegate trace_set_clr_event() to workqueue to avoid
such lock dependency.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20250224221637.4780-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin

dma/contiguous: avoid warning about unused size_bytes

2025-05-02T05:46:53+00:00

[ Upstream commit d7b98ae5221007d3f202746903d4c21c7caf7ea9 ]

When building with W=1, this variable is unused for configs with
CONFIG_CMA_SIZE_SEL_PERCENTAGE=y:

kernel/dma/contiguous.c:67:26: error: 'size_bytes' defined but not used [-Werror=unused-const-variable=]

Change this to a macro to avoid the warning.

Fixes: c64be2bb1c6e ("drivers: add Contiguous Memory Allocator")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250409151557.3890443-1-arnd@kernel.org
Signed-off-by: Sasha Levin

tracing: Verify event formats that have "%*p.."

2025-05-02T05:46:49+00:00

[ Upstream commit ea8d7647f9ddf1f81e2027ed305299797299aa03 ]

The trace event verifier checks the formats of trace events to make sure
that they do not point at memory that is not in the trace event itself or
in data that will never be freed. If an event references data that was
allocated when the event triggered and that same data is freed before the
event is read, then the kernel can crash by reading freed memory.

The verifier runs at boot up (or module load) and scans the print formats
of the events and checks their arguments to make sure that dereferenced
pointers are safe. If the format uses "%*p.." the verifier will ignore it,
and that could be dangerous. Cover this case as well.

Also add to the sample code a use case of "%*pbl".

Link: https://lore.kernel.org/all/bcba4d76-2c3f-4d11-baf0-02905db953dd@oracle.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers")
Link: https://lore.kernel.org/20250327195311.2d89ec66@gandalf.local.home
Reported-by: Libo Chen 
Reviewed-by: Libo Chen 
Tested-by: Libo Chen 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Sasha Levin

module: sign with sha512 instead of sha1 by default

2025-05-02T05:46:49+00:00

commit f3b93547b91ad849b58eb5ab2dd070950ad7beb3 upstream.

Switch away from using sha1 for module signing by default and use the
more modern sha512 instead, which is what among others Arch, Fedora,
RHEL, and Ubuntu are currently using for their kernels.

Sha1 has not been considered secure against well-funded opponents since
2005[1]; since 2011 the NIST and other organizations furthermore
recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora
Linux 41+[3], and likely some other current and future distributions
reject the creation of sha1 signatures, which leads to a build error of
allmodconfig configurations:

  80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342:
  make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1
  make[4]: *** Deleting file 'certs/signing_key.pem'
  make[4]: *** Waiting for unfinished jobs....
  make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2
  make[2]: *** [.../Makefile:1936: .] Error 2
  make[1]: *** [.../Makefile:224: __sub-make] Error 2
  make[1]: Leaving directory '...'
  make: *** [Makefile:224: __sub-make] Error 2

This change makes allmodconfig work again and sets a default that is
more appropriate for current and future users, too.

Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1]
Link: https://csrc.nist.gov/projects/hash-functions [2]
Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3]
Signed-off-by: Thorsten Leemhuis 
Reviewed-by: Sami Tolvanen 
Tested-by: kdevops  [0]
Link: https://github.com/linux-kdevops/linux-modules-kpd/actions/runs/11420092929/job/31775404330 [0]
Link: https://lore.kernel.org/r/52ee32c0c92afc4d3263cea1f8a1cdc809728aff.1729088288.git.linux@leemhuis.info
Signed-off-by: Petr Pavlu 
Signed-off-by: Greg Kroah-Hartman

bpf: Prevent tail call between progs attached to different hooks

2025-04-25T08:44:03+00:00

commit 28ead3eaabc16ecc907cfb71876da028080f6356 upstream.

bpf progs can be attached to kernel functions, and the attached functions
can take different parameters or return different return values. If
prog attached to one kernel function tail calls prog attached to another
kernel function, the ctx access or return value verification could be
bypassed.

For example, if prog1 is attached to func1 which takes only 1 parameter
and prog2 is attached to func2 which takes two parameters. Since verifier
assumes the bpf ctx passed to prog2 is constructed based on func2's
prototype, verifier allows prog2 to access the second parameter from
the bpf ctx passed to it. The problem is that verifier does not prevent
prog1 from passing its bpf ctx to prog2 via tail call. In this case,
the bpf ctx passed to prog2 is constructed from func1 instead of func2,
that is, the assumption for ctx access verification is bypassed.

Another example, if BPF LSM prog1 is attached to hook file_alloc_security,
and BPF LSM prog2 is attached to hook bpf_lsm_audit_rule_known. Verifier
knows the return value rules for these two hooks, e.g. it is legal for
bpf_lsm_audit_rule_known to return positive number 1, and it is illegal
for file_alloc_security to return positive number. So verifier allows
prog2 to return positive number 1, but does not allow prog1 to return
positive number. The problem is that verifier does not prevent prog1
from calling prog2 via tail call. In this case, prog2's return value 1
will be used as the return value for prog1's hook file_alloc_security.
That is, the return value rule is bypassed.

This patch adds restriction for tail call to prevent such bypasses.

Signed-off-by: Xu Kuohai 
Link: https://lore.kernel.org/r/20240719110059.797546-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
[Minor conflict resolved due to code context change.]
Signed-off-by: Jianqi Ren 
Signed-off-by: He Zhe 
Signed-off-by: Greg Kroah-Hartman

bpf: avoid holding freeze_mutex during mmap operation

2025-04-25T08:44:03+00:00

commit bc27c52eea189e8f7492d40739b7746d67b65beb upstream.

We use map->freeze_mutex to prevent races between map_freeze() and
memory mapping BPF map contents with writable permissions. The way we
naively do this means we'll hold freeze_mutex for entire duration of all
the mm and VMA manipulations, which is completely unnecessary. This can
potentially also lead to deadlocks, as reported by syzbot in [0].

So, instead, hold freeze_mutex only during writeability checks, bump
(proactively) "write active" count for the map, unlock the mutex and
proceed with mmap logic. And only if something went wrong during mmap
logic, then undo that "write active" counter increment.

  [0] https://lore.kernel.org/bpf/678dcbc9.050a0220.303755.0066.GAE@google.com/

Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Reported-by: syzbot+4dc041c686b7c816a71e@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/r/20250129012246.1515826-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov 
Signed-off-by: David Sauerwein 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix filter string testing

2025-04-25T08:43:55+00:00

commit a8c5b0ed89a3f2c81c6ae0b041394e6eea0e7024 upstream.

The filter string testing uses strncpy_from_kernel/user_nofault() to
retrieve the string to test the filter against. The if() statement was
incorrect as it considered 0 as a fault, when it is only negative that it
faulted.

Running the following commands:

  # cd /sys/kernel/tracing
  # echo "filename.ustring ~ \"/proc*\"" > events/syscalls/sys_enter_openat/filter
  # echo 1 > events/syscalls/sys_enter_openat/enable
  # ls /proc/$$/maps
  # cat trace

Would produce nothing, but with the fix it will produce something like:

      ls-1192    [007] .....  8169.828333: sys_openat(dfd: ffffffffffffff9c, filename: 7efc18359904, flags: 80000, mode: 0)

Link: https://lore.kernel.org/all/CAEf4BzbVPQ=BjWztmEwBPRKHUwNfKBkS3kce-Rzka6zvbQeVpg@mail.gmail.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Link: https://lore.kernel.org/20250417183003.505835fb@gandalf.local.home
Fixes: 77360f9bbc7e5 ("tracing: Add test for user space strings when filtering on string pointers")
Reported-by: Andrii Nakryiko 
Reported-by: Mykyta Yatsenko 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

cpufreq/sched: Fix the usage of CPUFREQ_NEED_UPDATE_LIMITS

2025-04-25T08:43:51+00:00

[ Upstream commit cfde542df7dd51d26cf667f4af497878ddffd85a ]

Commit 8e461a1cb43d ("cpufreq: schedutil: Fix superfluous updates caused
by need_freq_update") modified sugov_should_update_freq() to set the
need_freq_update flag only for drivers with CPUFREQ_NEED_UPDATE_LIMITS
set, but that flag generally needs to be set when the policy limits
change because the driver callback may need to be invoked for the new
limits to take effect.

However, if the return value of cpufreq_driver_resolve_freq() after
applying the new limits is still equal to the previously selected
frequency, the driver callback needs to be invoked only in the case
when CPUFREQ_NEED_UPDATE_LIMITS is set (which means that the driver
specifically wants its callback to be invoked every time the policy
limits change).

Update the code accordingly to avoid missing policy limits changes for
drivers without CPUFREQ_NEED_UPDATE_LIMITS.

Fixes: 8e461a1cb43d ("cpufreq: schedutil: Fix superfluous updates caused by need_freq_update")
Closes: https://lore.kernel.org/lkml/Z_Tlc6Qs-tYpxWYb@linaro.org/
Reported-by: Stephan Gerhold 
Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Christian Loehle 
Link: https://patch.msgid.link/3010358.e9J7NaK4W3@rjwysocki.net
Signed-off-by: Sasha Levin

ftrace: Add cond_resched() to ftrace_graph_set_hash()

2025-04-25T08:43:44+00:00

commit 42ea22e754ba4f2b86f8760ca27f6f71da2d982c upstream.

When the kernel contains a large number of functions that can be traced,
the loop in ftrace_graph_set_hash() may take a lot of time to execute.
This may trigger the softlockup watchdog.

Add cond_resched() within the loop to allow the kernel to remain
responsive even when processing a large number of functions.

This matches the cond_resched() that is used in other locations of the
code that iterates over all functions that can be traced.

Cc: stable@vger.kernel.org
Fixes: b9b0c831bed26 ("ftrace: Convert graph filter to use hash tables")
Link: https://lore.kernel.org/tencent_3E06CE338692017B5809534B9C5C03DA7705@qq.com
Signed-off-by: zhoumin 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

locking/lockdep: Decrease nr_unused_locks if lock unused in zap_class()

2025-04-25T08:43:41+00:00

commit 495f53d5cca0f939eaed9dca90b67e7e6fb0e30c upstream.

Currently, when a lock class is allocated, nr_unused_locks will be
increased by 1, until it gets used: nr_unused_locks will be decreased by
1 in mark_lock(). However, one scenario is missed: a lock class may be
zapped without even being used once. This could result into a situation
that nr_unused_locks != 0 but no unused lock class is active in the
system, and when `cat /proc/lockdep_stats`, a WARN_ON() will
be triggered in a CONFIG_DEBUG_LOCKDEP=y kernel:

  [...] DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused)
  [...] WARNING: CPU: 41 PID: 1121 at kernel/locking/lockdep_proc.c:283 lockdep_stats_show+0xba9/0xbd0

And as a result, lockdep will be disabled after this.

Therefore, nr_unused_locks needs to be accounted correctly at
zap_class() time.

Signed-off-by: Boqun Feng 
Signed-off-by: Ingo Molnar 
Reviewed-by: Waiman Long 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250326180831.510348-1-boqun.feng@gmail.com
Signed-off-by: Greg Kroah-Hartman