Impact: no default -fno-stack-protector if stackp is enabled, cleanup
Stackprotector make rules had the following problems.
* cc support test and warning are scattered across makefile and
kernel/panic.c.
* -fno-stack-protector was always added regardless of configuration.
Update such that cc support test and warning are contained in makefile
and -fno-stack-protector is added iff stackp is turned off. While at
it, prepare for 32bit support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, eliminate code
now that warn_on_slowpath() uses warn_slowpath(...,NULL), we can
eliminate warn_on_slowpath() altogether and use warn_slowpath().
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend WARN_ON() output with DMI_PRODUCT_NAME
It's very useful for many low level WARN_ON's to find out which
motherboard has the broken BIOS etc... this patch adds a printk
to the WARN_ON code for this.
On architectures without DMI, gcc should optimize the code out.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, code reduction
warn_slowpath is a superset of warn_on_slowpath; just have
warn_on_slowpath call warn_slowpath with a NULL 3rd argument.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This allows them to be examined and set after boot, plus means they
actually give errors if they are misused (eg. panic=yes).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It's somewhat unlikely that it happens, but right now a race window
between interrupts or machine checks or oopses could corrupt the tainted
bitmap because it is modified in a non atomic fashion.
Convert the taint variable to an unsigned long and use only atomic bit
operations on it.
Unfortunately this means the intvec sysctl functions cannot be used on it
anymore.
It turned out the taint sysctl handler could actually be simplified a bit
(since it only increases capabilities) so this patch actually removes
code.
[akpm@linux-foundation.org: remove unneeded include]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to add a flag for all code that is in the drivers/staging/
directory to prevent all other kernel developers from worrying about
issues here, and to notify users that the drivers might not be as good
as they are normally used to.
Based on code from Andreas Gruenbacher and Jeff Mahoney to provide a
TAINT flag for the support level of a kernel module in the Novell
enterprise kernel release.
This is the kernel portion of this feature, the ability for the flag to
be set needs to be done in the build process and will happen in a
follow-up patch.
Cc: Andreas Gruenbacher <agruen@suse.de>
Cc: Jeff Mahoney <jeffm@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add a WARN() macro that acts like WARN_ON(), with the added feature that it
takes a printk like argument that is printed as part of the warning message.
[akpm@linux-foundation.org: fix printk arguments]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
turns out gcc generates such stackprotector-failure sequences
in certain circumstances:
movq -8(%rbp), %rax # D.16032,
xorq %gs:40, %rax #,
jne .L17 #,
leave
ret
.L17:
call __stack_chk_fail #
.size __stack_chk_test_func, .-__stack_chk_test_func
.section .init.text,"ax",@progbits
.type panic_setup, @function
panic_setup:
pushq %rbp #
note that there's no jump back to the failing context after the
call to __stack_chk_fail - i.e. it has a ((noreturn)) attribute.
Which is fair enough in the normal case but kills the self-test.
(as we cannot reliably return in the self-test)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Clean up the code by removing no longer needed code;
make sure the pda is updated and kept in sync
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
check stackprotector functionality by manipulating the canary briefly
during bootup.
far more robust than trying to overflow the stack. (which is architecture
dependent, etc.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If the user selects the stack-protector config option, but does not have
a gcc that has the right bits enabled (for example because it isn't build
with a glibc that supports TLS, as is common for cross-compilers, but also
because it may be too old), then the runtime test fails right now.
This patch adds a warning message for this scenario. This warning accomplishes
two goals
1) the user is informed that the security option he selective isn't available
2) the user is suggested to turn of the CONFIG option that won't work for him,
and would make the runtime test fail anyway.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds a simple self-test capability to the stackprotector
feature. The test deliberately overflows a stack buffer and then
checks if the canary trap function gets called.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
if CONFIG_DEBUG_BUGVERBOSE is set then the user most definitely wanted
to see as much information about kernel crashes as possible - so give
them at least a stack dump.
this is particularly useful for stackprotector related panics, where
the stacktrace can give us the exact location of the (attempted)
attack.
Pointed out by pageexec@freemail.hu in the stackprotector breakage
threads.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
pointed out by pageexec@freemail.hu:
we just simply panic() when there's a stackprotector attack - giving
the attacked person no information about what kernel code the attack went
against.
print out the attacked function.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The kernel is sent to tainted within the warn_on_slowpath() function, and
whenever a warning occurs the new taint flag 'W' is set. This is useful to
know if a warning occurred before a BUG by preserving the warning as a flag
in the taint state.
This does not work on architectures where WARN_ON has its own definition.
These archs are:
1. s390
2. superh
3. avr32
4. parisc
The maintainers of these architectures have been added in the Cc: list
in this email to alert them to the situation.
The documentation in oops-tracing.txt has been updated to include the
new flag.
Signed-off-by: Nur Hussein <nurhussein@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
