Pull module fix from Rusty Russell:
"A single panic fix for a rare race, stable CC'd"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
modules, lock around setting of MODULE_STATE_UNFORMED
A panic was seen in the following sitation.
There are two threads running on the system. The first thread is a system
monitoring thread that is reading /proc/modules. The second thread is
loading and unloading a module (in this example I'm using my simple
dummy-module.ko). Note, in the "real world" this occurred with the qlogic
driver module.
When doing this, the following panic occurred:
------------[ cut here ]------------
kernel BUG at kernel/module.c:3739!
invalid opcode: 0000 [#1] SMP
Modules linked in: binfmt_misc sg nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel lrw igb gf128mul glue_helper iTCO_wdt iTCO_vendor_support ablk_helper ptp sb_edac cryptd pps_core edac_core shpchp i2c_i801 pcspkr wmi lpc_ich ioatdma mfd_core dca ipmi_si nfsd ipmi_msghandler auth_rpcgss nfs_acl lockd sunrpc xfs libcrc32c sr_mod cdrom sd_mod crc_t10dif crct10dif_common mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ttm isci drm libsas ahci libahci scsi_transport_sas libata i2c_core dm_mirror dm_region_hash dm_log dm_mod [last unloaded: dummy_module]
CPU: 37 PID: 186343 Comm: cat Tainted: GF O-------------- 3.10.0+ #7
Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013
task: ffff8807fd2d8000 ti: ffff88080fa7c000 task.ti: ffff88080fa7c000
RIP: 0010:[<ffffffff810d64c5>] [<ffffffff810d64c5>] module_flags+0xb5/0xc0
RSP: 0018:ffff88080fa7fe18 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffffffffa03b5200 RCX: 0000000000000000
RDX: 0000000000001000 RSI: ffff88080fa7fe38 RDI: ffffffffa03b5000
RBP: ffff88080fa7fe28 R08: 0000000000000010 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000000000f R12: ffffffffa03b5000
R13: ffffffffa03b5008 R14: ffffffffa03b5200 R15: ffffffffa03b5000
FS: 00007f6ae57ef740(0000) GS:ffff88101e7a0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000404f70 CR3: 0000000ffed48000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
ffffffffa03b5200 ffff8810101e4800 ffff88080fa7fe70 ffffffff810d666c
ffff88081e807300 000000002e0f2fbf 0000000000000000 ffff88100f257b00
ffffffffa03b5008 ffff88080fa7ff48 ffff8810101e4800 ffff88080fa7fee0
Call Trace:
[<ffffffff810d666c>] m_show+0x19c/0x1e0
[<ffffffff811e4d7e>] seq_read+0x16e/0x3b0
[<ffffffff812281ed>] proc_reg_read+0x3d/0x80
[<ffffffff811c0f2c>] vfs_read+0x9c/0x170
[<ffffffff811c1a58>] SyS_read+0x58/0xb0
[<ffffffff81605829>] system_call_fastpath+0x16/0x1b
Code: 48 63 c2 83 c2 01 c6 04 03 29 48 63 d2 eb d9 0f 1f 80 00 00 00 00 48 63 d2 c6 04 13 2d 41 8b 0c 24 8d 50 02 83 f9 01 75 b2 eb cb <0f> 0b 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41
RIP [<ffffffff810d64c5>] module_flags+0xb5/0xc0
RSP <ffff88080fa7fe18>
Consider the two processes running on the system.
CPU 0 (/proc/modules reader)
CPU 1 (loading/unloading module)
CPU 0 opens /proc/modules, and starts displaying data for each module by
traversing the modules list via fs/seq_file.c:seq_open() and
fs/seq_file.c:seq_read(). For each module in the modules list, seq_read
does
op->start() <-- this is a pointer to m_start()
op->show() <- this is a pointer to m_show()
op->stop() <-- this is a pointer to m_stop()
The m_start(), m_show(), and m_stop() module functions are defined in
kernel/module.c. The m_start() and m_stop() functions acquire and release
the module_mutex respectively.
ie) When reading /proc/modules, the module_mutex is acquired and released
for each module.
m_show() is called with the module_mutex held. It accesses the module
struct data and attempts to write out module data. It is in this code
path that the above BUG_ON() warning is encountered, specifically m_show()
calls
static char *module_flags(struct module *mod, char *buf)
{
int bx = 0;
BUG_ON(mod->state == MODULE_STATE_UNFORMED);
...
The other thread, CPU 1, in unloading the module calls the syscall
delete_module() defined in kernel/module.c. The module_mutex is acquired
for a short time, and then released. free_module() is called without the
module_mutex. free_module() then sets mod->state = MODULE_STATE_UNFORMED,
also without the module_mutex. Some additional code is called and then the
module_mutex is reacquired to remove the module from the modules list:
/* Now we can delete it from the lists */
mutex_lock(&module_mutex);
stop_machine(__unlink_module, mod, NULL);
mutex_unlock(&module_mutex);
This is the sequence of events that leads to the panic.
CPU 1 is removing dummy_module via delete_module(). It acquires the
module_mutex, and then releases it. CPU 1 has NOT set dummy_module->state to
MODULE_STATE_UNFORMED yet.
CPU 0, which is reading the /proc/modules, acquires the module_mutex and
acquires a pointer to the dummy_module which is still in the modules list.
CPU 0 calls m_show for dummy_module. The check in m_show() for
MODULE_STATE_UNFORMED passed for dummy_module even though it is being
torn down.
Meanwhile CPU 1, which has been continuing to remove dummy_module without
holding the module_mutex, now calls free_module() and sets
dummy_module->state to MODULE_STATE_UNFORMED.
CPU 0 now calls module_flags() with dummy_module and ...
static char *module_flags(struct module *mod, char *buf)
{
int bx = 0;
BUG_ON(mod->state == MODULE_STATE_UNFORMED);
and BOOM.
Acquire and release the module_mutex lock around the setting of
MODULE_STATE_UNFORMED in the teardown path, which should resolve the
problem.
Testing: In the unpatched kernel I can panic the system within 1 minute by
doing
while (true) do insmod dummy_module.ko; rmmod dummy_module.ko; done
and
while (true) do cat /proc/modules; done
in separate terminals.
In the patched kernel I was able to run just over one hour without seeing
any issues. I also verified the output of panic via sysrq-c and the output
of /proc/modules looks correct for all three states for the dummy_module.
dummy_module 12661 0 - Unloading 0xffffffffa03a5000 (OE-)
dummy_module 12661 0 - Live 0xffffffffa03bb000 (OE)
dummy_module 14015 1 - Loading 0xffffffffa03a5000 (OE+)
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Pull arm64 updates from Catalin Marinas:
- eBPF JIT compiler for arm64
- CPU suspend backend for PSCI (firmware interface) with standard idle
states defined in DT (generic idle driver to be merged via a
different tree)
- Support for CONFIG_DEBUG_SET_MODULE_RONX
- Support for unmapped cpu-release-addr (outside kernel linear mapping)
- set_arch_dma_coherent_ops() implemented and bus notifiers removed
- EFI_STUB improvements when base of DRAM is occupied
- Typos in KGDB macros
- Clean-up to (partially) allow kernel building with LLVM
- Other clean-ups (extern keyword, phys_addr_t usage)
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (51 commits)
arm64: Remove unneeded extern keyword
ARM64: make of_device_ids const
arm64: Use phys_addr_t type for physical address
aarch64: filter $x from kallsyms
arm64: Use DMA_ERROR_CODE to denote failed allocation
arm64: Fix typos in KGDB macros
arm64: insn: Add return statements after BUG_ON()
arm64: debug: don't re-enable debug exceptions on return from el1_dbg
Revert "arm64: dmi: Add SMBIOS/DMI support"
arm64: Implement set_arch_dma_coherent_ops() to replace bus notifiers
of: amba: use of_dma_configure for AMBA devices
arm64: dmi: Add SMBIOS/DMI support
arm64: Correct ftrace calls to aarch64_insn_gen_branch_imm()
arm64:mm: initialize max_mapnr using function set_max_mapnr
setup: Move unmask of async interrupts after possible earlycon setup
arm64: LLVMLinux: Fix inline arm64 assembly for use with clang
arm64: pageattr: Correctly adjust unaligned start addresses
net: bpf: arm64: fix module memory leak when JIT image build fails
arm64: add PSCI CPU_SUSPEND based cpu_suspend support
arm64: kernel: introduce cpu_init_idle CPU operation
...
Similar to ARM, AArch64 is generating $x and $d syms... which isn't
terribly helpful when looking at %pF output and the like. Filter those
out in kallsyms, modpost and when looking at module symbols.
Seems simplest since none of these check EM_ARM anyway, to just add it
to the strchr used, rather than trying to make things overly
complicated.
initcall_debug improves:
dmesg_before.txt: initcall $x+0x0/0x154 [sg] returned 0 after 26331 usecs
dmesg_after.txt: initcall init_sg+0x0/0x154 [sg] returned 0 after 15461 usecs
Signed-off-by: Kyle McMartin <kyle@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The commit
4982223e51 module: set nx before marking module MODULE_STATE_COMING.
introduced a regression: if a module fails to parse its arguments or
if mod_sysfs_setup fails, then the module's memory will be freed
while still read-only. Anything that reuses that memory will crash
as soon as it tries to write to it.
Cc: stable@vger.kernel.org # v3.16
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Symbols starting with .L are ELF local symbols and should not appear
in ELF symbol tables. However, unfortunately ARM binutils leaks the
.LANCHOR symbols into the symbol table, which leads kallsyms to report
these symbols rather than the real name. It is not very useful when
%pf reports symbols against these leaked .LANCHOR symbols.
Arrange for kallsyms to ignore these symbols using the same mechanism
that is used for the ARM mapping symbols.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It is just a small optimization that allows to replace few
occurrences of within_module_init() || within_module_core()
with a single call.
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Per further discussion with NIST, the requirements for FIPS state that
we only need to panic the system on failed kernel module signature checks
for crypto subsystem modules. This moves the fips-mode-only module
signature check out of the generic module loading code, into the crypto
subsystem, at points where we can catch both algorithm module loads and
mode module loads. At the same time, make CONFIG_CRYPTO_FIPS dependent on
CONFIG_MODULE_SIG, as this is entirely necessary for FIPS mode.
v2: remove extraneous blank line, perform checks in static inline
function, drop no longer necessary fips.h include.
CC: "David S. Miller" <davem@davemloft.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Stephan Mueller <stephan.mueller@atsec.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull module updates from Rusty Russell:
"Most of this is cleaning up various driver sysfs permissions so we can
re-add the perm check (we unified the module param and sysfs checks,
but the module ones were stronger so we weakened them temporarily).
Param parsing gets documented, and also "--" now forces args to be
handed to init (and ignored by the kernel).
Module NX/RO protections get tightened: we now set them before calling
parse_args()"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
module: set nx before marking module MODULE_STATE_COMING.
samples/kobject/: avoid world-writable sysfs files.
drivers/hid/hid-picolcd_fb: avoid world-writable sysfs files.
drivers/staging/speakup/: avoid world-writable sysfs files.
drivers/regulator/virtual: avoid world-writable sysfs files.
drivers/scsi/pm8001/pm8001_ctl.c: avoid world-writable sysfs files.
drivers/hid/hid-lg4ff.c: avoid world-writable sysfs files.
drivers/video/fbdev/sm501fb.c: avoid world-writable sysfs files.
drivers/mtd/devices/docg3.c: avoid world-writable sysfs files.
speakup: fix incorrect perms on speakup_acntsa.c
cpumask.h: silence warning with -Wsign-compare
Documentation: Update kernel-parameters.tx
param: hand arguments after -- straight to init
modpost: Fix resource leak in read_dump()
We currently set RO & NX on modules very late: after we move them from
MODULE_STATE_UNFORMED to MODULE_STATE_COMING, and after we call
parse_args() (which can exec code in the module).
Much better is to do it in complete_formation() and then call
the notifier.
This means that the notifiers will be called on a module which
is already RO & NX, so that may cause problems (ftrace already
changed so they're unaffected).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pull module fixes from Rusty Russell:
"Fixed one missing place for the new taint flag, and remove a warning
giving only false positives (now we finally figured out why)"
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
module: remove warning about waiting module removal.
Fix: tracing: use 'E' instead of 'X' for unsigned module taint flag
A race exists between module loading and enabling of function tracer.
CPU 1 CPU 2
----- -----
load_module()
module->state = MODULE_STATE_COMING
register_ftrace_function()
mutex_lock(&ftrace_lock);
ftrace_startup()
update_ftrace_function();
ftrace_arch_code_modify_prepare()
set_all_module_text_rw();
<enables-ftrace>
ftrace_arch_code_modify_post_process()
set_all_module_text_ro();
[ here all module text is set to RO,
including the module that is
loading!! ]
blocking_notifier_call_chain(MODULE_STATE_COMING);
ftrace_init_module()
[ tries to modify code, but it's RO, and fails!
ftrace_bug() is called]
When this race happens, ftrace_bug() will produces a nasty warning and
all of the function tracing features will be disabled until reboot.
The simple solution is to treate module load the same way the core
kernel is treated at boot. To hardcode the ftrace function modification
of converting calls to mcount into nops. This is done in init/main.c
there's no reason it could not be done in load_module(). This gives
a better control of the changes and doesn't tie the state of the
module to its notifiers as much. Ftrace is special, it needs to be
treated as such.
The reason this would work, is that the ftrace_module_init() would be
called while the module is in MODULE_STATE_UNFORMED, which is ignored
by the set_all_module_text_ro() call.
Link: http://lkml.kernel.org/r/1395637826-3312-1-git-send-email-indou.takao@jp.fujitsu.com
Reported-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@vger.kernel.org # 2.6.38+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The kernel passes any args it doesn't need through to init, except it
assumes anything containing '.' belongs to the kernel (for a module).
This change means all users can clearly distinguish which arguments
are for init.
For example, the kernel uses debug ("dee-bug") to mean log everything to
the console, where systemd uses the debug from the Scandinavian "day-boog"
meaning "fail to boot". If a future versions uses argv[] instead of
reading /proc/cmdline, this confusion will be avoided.
eg: test 'FOO="this is --foo"' -- 'systemd.debug="true true true"'
Gives:
argv[0] = '/debug-init'
argv[1] = 'test'
argv[2] = 'systemd.debug=true true true'
envp[0] = 'HOME=/'
envp[1] = 'TERM=linux'
envp[2] = 'FOO=this is --foo'
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We remove the waiting module removal in commit 3f2b9c9cdf (September
2013), but it turns out that modprobe in kmod (< version 16) was
asking for waiting module removal. No one noticed since modprobe would
check for 0 usage immediately before trying to remove the module, and
the race is unlikely.
However, it means that anyone running old (but not ancient) kmod
versions is hitting the printk designed to see if anyone was running
"rmmod -w". All reports so far have been false positives, so remove
the warning.
Fixes: 3f2b9c9cdf
Reported-by: Valerio Vanni <valerio.vanni@inwind.it>
Cc: Elliott, Robert (Server Storage) <Elliott@hp.com>
Cc: stable@kernel.org
Acked-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The initialization of a structure is not subject to synchronization.
The use of __this_cpu would trigger a false positive with the additional
preemption checks for __this_cpu ops.
So simply disable the check through the use of raw_cpu ops.
Trace:
__this_cpu_write operation in preemptible [00000000] code: modprobe/286
caller is __this_cpu_preempt_check+0x38/0x60
CPU: 3 PID: 286 Comm: modprobe Tainted: GF 3.12.0-rc4+ #187
Call Trace:
dump_stack+0x4e/0x82
check_preemption_disabled+0xec/0x110
__this_cpu_preempt_check+0x38/0x60
load_module+0xcfd/0x2650
SyS_init_module+0xa6/0xd0
tracesys+0xe1/0xe6
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull module updates from Rusty Russell:
"Nothing major: the stricter permissions checking for sysfs broke a
staging driver; fix included. Greg KH said he'd take the patch but
hadn't as the merge window opened, so it's included here to avoid
breaking build"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
staging: fix up speakup kobject mode
Use 'E' instead of 'X' for unsigned module taint flag.
VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.
kallsyms: fix percpu vars on x86-64 with relocation.
kallsyms: generalize address range checking
module: LLVMLinux: Remove unused function warning from __param_check macro
Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE
module: remove MODULE_GENERIC_TABLE
module: allow multiple calls to MODULE_DEVICE_TABLE() per module
module: use pr_cont
Pull x86 LTO changes from Peter Anvin:
"More infrastructure work in preparation for link-time optimization
(LTO). Most of these changes is to make sure symbols accessed from
assembly code are properly marked as visible so the linker doesn't
remove them.
My understanding is that the changes to support LTO are still not
upstream in binutils, but are on the way there. This patchset should
conclude the x86-specific changes, and remaining patches to actually
enable LTO will be fed through the Kbuild tree (other than keeping up
with changes to the x86 code base, of course), although not
necessarily in this merge window"
* 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
Kbuild, lto: Handle basic LTO in modpost
Kbuild, lto: Disable LTO for asm-offsets.c
Kbuild, lto: Add a gcc-ld script to let run gcc as ld
Kbuild, lto: add ld-version and ld-ifversion macros
Kbuild, lto: Drop .number postfixes in modpost
Kbuild, lto, workaround: Don't warn for initcall_reference in modpost
lto: Disable LTO for sys_ni
lto: Handle LTO common symbols in module loader
lto, workaround: Add workaround for initcall reordering
lto: Make asmlinkage __visible
x86, lto: Disable LTO for the x86 VDSO
initconst, x86: Fix initconst mistake in ts5500 code
initconst: Fix initconst mistake in dcdbas
asmlinkage: Make trace_hardirqs_on/off_caller visible
asmlinkage, x86: Fix 32bit memcpy for LTO
asmlinkage Make __stack_chk_failed and memcmp visible
asmlinkage: Mark rwsem functions that can be called from assembler asmlinkage
asmlinkage: Make main_extable_sort_needed visible
asmlinkage, mutex: Mark __visible
asmlinkage: Make trace_hardirq visible
...
Takashi Iwai <tiwai@suse.de> says:
> The letter 'X' has been already used for SUSE kernels for very long
> time, to indicate the external supported modules. Can the new flag be
> changed to another letter for avoiding conflict...?
> (BTW, we also use 'N' for "no support", too.)
Note: this code should be cleaned up, so we don't have such maps in
three places!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Users have reported being unable to trace non-signed modules loaded
within a kernel supporting module signature.
This is caused by tracepoint.c:tracepoint_module_coming() refusing to
take into account tracepoints sitting within force-loaded modules
(TAINT_FORCED_MODULE). The reason for this check, in the first place, is
that a force-loaded module may have a struct module incompatible with
the layout expected by the kernel, and can thus cause a kernel crash
upon forced load of that module on a kernel with CONFIG_TRACEPOINTS=y.
Tracepoints, however, specifically accept TAINT_OOT_MODULE and
TAINT_CRAP, since those modules do not lead to the "very likely system
crash" issue cited above for force-loaded modules.
With kernels having CONFIG_MODULE_SIG=y (signed modules), a non-signed
module is tainted re-using the TAINT_FORCED_MODULE taint flag.
Unfortunately, this means that Tracepoints treat that module as a
force-loaded module, and thus silently refuse to consider any tracepoint
within this module.
Since an unsigned module does not fit within the "very likely system
crash" category of tainting, add a new TAINT_UNSIGNED_MODULE taint flag
to specifically address this taint behavior, and accept those modules
within Tracepoints. We use the letter 'X' as a taint flag character for
a module being loaded that doesn't know how to sign its name (proposed
by Steven Rostedt).
Also add the missing 'O' entry to trace event show_module_flags() list
for the sake of completeness.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
NAKed-by: Ingo Molnar <mingo@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: David Howells <dhowells@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When dumping loaded modules, we print them one by one in separate
printks. Let's use pr_cont as they are continuation prints.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
