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powerpc: make stack walking KASAN-safe

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Make our stack-walking code KASAN-safe by using __no_sanitize_address.
Generic code, arm64, s390 and x86 all make accesses unchecked for similar
sorts of reasons: when unwinding a stack, we might touch memory that KASAN
has marked as being out-of-bounds. In ppc64 KASAN development, I hit this
sometimes when checking for an exception frame - because we're checking
an arbitrary offset into the stack frame.

See commit 2095574632 ("s390/kasan: avoid false positives during stack
unwind"), commit bcaf669b4b ("arm64: disable kasan when accessing
frame->fp in unwind_frame"), commit 91e08ab0c8 ("x86/dumpstack:
Prevent KASAN false positive warnings") and commit 6e22c83664
("tracing, kasan: Silence Kasan warning in check_stack of stack_tracer").

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210614120907.1952321-1-dja@axtens.net
This commit is contained in:
Daniel Axtens 2021-06-14 22:09:07 +10:00 committed by Michael Ellerman
parent d81090ed44
commit b112fb913b
3 changed files with 8 additions and 7 deletions
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5
arch/powerpc/kernel/process.c
View file

@ -2133,8 +2133,9 @@ unsigned long get_wchan(struct task_struct *p)
static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
void show_stack(struct task_struct *tsk, unsigned long *stack,
const char *loglvl)
void __no_sanitize_address show_stack(struct task_struct *tsk,
unsigned long *stack,
const char *loglvl)
{
unsigned long sp, ip, lr, newsp;
int count = 0;

8
arch/powerpc/kernel/stacktrace.c
View file

@ -23,8 +23,8 @@
#include <asm/paca.h>
void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
{
unsigned long sp;
@ -61,8 +61,8 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
*
* If the task is not 'current', the caller *must* ensure the task is inactive.
*/
int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task)
int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task)
{
unsigned long sp;
unsigned long newsp;

2
arch/powerpc/perf/callchain.c
View file

@ -40,7 +40,7 @@ static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
return 0;
}
void
void __no_sanitize_address
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
unsigned long sp, next_sp;