Kees writes:
lkdtm updates for v5.17-rc1
- Fix printk() usage during recursion (Ard Biesheuvel)
- Fix rodata section to actually have contents (Christophe Leroy)
- Add notes about lkdtm_kernel_info usage (Kees Cook)
- Avoid stack-entropy selftest when LKDTM is disabled (Misono Tomohiro)
* tag 'lkdtm-v5.17-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
selftest/lkdtm: Skip stack-entropy test if lkdtm is not available
lkdtm: Fix content of section containing lkdtm_rodata_do_nothing()
lkdtm: avoid printk() in recursive_loop()
lkdtm: Note that lkdtm_kernel_info should be removed in the future
The recursive_loop() function is intended as a diagnostic to ensure that
exhausting the stack is caught and mitigated. Currently, it uses
pr_info() to ensure that the function has side effects that the compiler
cannot simply optimize away, so that the stack footprint does not get
reduced inadvertently.
The typical mitigation for stack overflow is to kill the task, and this
overflow may occur inside the call to pr_info(), which means it could be
holding the console lock when this happens. This means that the console
lock is never going to be released again, preventing the diagnostic
prints related to the stack overflow handling from being visible on the
console.
So let's replace the call to pr_info() with a call to
memzero_explicit(), which is not a 'magic' function name like memset()
or memcpy(), which the compiler may replace with plain loads and stores.
To ensure that the stack frames are nested rather than tail-called, put
the call to memzero_explicit() after the recursive call.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211007081235.382697-1-ardb@kernel.org
The case to u8 * is unnecessary here since the expression is already of
type u8 *.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
`buf` is cast to a const char *, but `buf` is already a const char *, so
the case is unnecessary.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
`buf` is cast to a const char *, but `buf` is already a const char *, so
the case is unnecessary.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The find.h APIs are designed to be used only on unsigned long arguments.
This can technically result in a over-read, but it is harmless in this
case. Regardless, fix it to avoid the warning seen under -Warray-bounds,
which we'd like to enable globally:
In file included from ./include/linux/bitmap.h:9,
from ./include/linux/cpumask.h:12,
from ./arch/x86/include/asm/cpumask.h:5,
from ./arch/x86/include/asm/msr.h:11,
from ./arch/x86/include/asm/processor.h:22,
from ./arch/x86/include/asm/cpufeature.h:5,
from ./arch/x86/include/asm/thread_info.h:53,
from ./include/linux/thread_info.h:60,
from ./arch/x86/include/asm/preempt.h:7,
from ./include/linux/preempt.h:78,
from ./include/linux/spinlock.h:55,
from ./include/linux/swait.h:7,
from ./include/linux/completion.h:12,
from drivers/iio/adc/stmpe-adc.c:10:
drivers/iio/adc/stmpe-adc.c: In function 'stmpe_adc_probe':
./include/linux/find.h:98:23: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'u32[1]' {aka 'unsigned int[1]'} [-Warray-bounds]
98 | val = *addr | ~GENMASK(size - 1, offset);
| ^~~~~
drivers/iio/adc/stmpe-adc.c:258:13: note: while referencing 'norequest_mask'
258 | u32 norequest_mask = 0;
| ^~~~~~~~~~~~~~
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
By flushing the output, iio_event_monitor can be more useful to programs
chained along with it.
iio_event_monitor stk3310 | awk '/rising/{system("my_unlockscreen.sh")} /falling/{system("my_lockscreen.sh")}'
Without this flush, the above example would buffer a number of events,
then after a while run the lock/unlock scripts several times.
Signed-off-by: Zach DeCook <zachdecook@librem.one>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Drvdata is typically used by drivers to attach driver specific data to a
device. It is used to retrieve driver specific information when only the
device to which the data is attached is available.
In the IIO core in the `iio_device_alloc()` function we call
`iio_device_set_drvdata(indio_dev, indio_dev)`. This sets the drvdata of
the IIO device to itself.
This is rather unnecessary since if we have a pointer to the IIO device to
call `iio_device_get_drvdata()` on it we don't need to call the function
since we already have the pointer. If we only have a pointer to the `struct
device` we can use `dev_to_iio_dev()` to get the IIO device from it.
Furthermore the drvdata is supposed to be reserved for drivers, so it
should not be used by the IIO core in the first place.
The `set_drvdata()` has been around from the very beginning of the IIO
framework and back then it was used in the IIO device sysfs attribute
handling code. But that was subsequently replaced with a `dev_to_iio_dev()`
in commit e53f5ac52e ("iio: Use dev_to_iio_dev()") and other cleanups.
The self `set_drvdata()` is now no longer needed and can be removed.
Verified that there no longer any users by checking for potential users
using the following two coccinelle scripts and reviewing that none of the
matches are problematic code.
<smpl>
@@
struct iio_dev *iio_dev;
expression dev;
identifier fn !~ "(remove|resume|suspend)";
@@
fn(...)
{
...
*iio_dev = dev_get_drvdata(dev)
...
}
</smpl>
<smpl>
@r1@
position p;
struct iio_dev *indio_dev;
identifier dev_fn =~ "^dev_";
identifier devm_fn =~ "^devm_";
@@
(
dev_fn
|
devm_fn
)
(&indio_dev@p->dev, ...)
@@
struct iio_dev *indio_dev;
position p != r1.p;
@@
*&indio_dev@p->dev</smpl>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Bhaumik Bhatt
Loic Poulain
Slark Xiao
Greg Kroah-Hartman
Misono Tomohiro
Christophe Leroy
Ard Biesheuvel
Kees Cook
Jonathan Cameron
Mihail Chindris
Antoniu Miclaus
Lars-Peter Clausen
Minghao Chi
Dan Carpenter
Xiang wangx
Zach DeCook
Jason Wang