mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-27 04:47:05 +00:00
Code Issues Releases Wiki Activity

x86/show_trace_log_lvl: Ensure stack pointer is aligned, again

Browse source 
commit 2e4be0d011 upstream.

The commit e335bb51cc ("x86/unwind: Ensure stack pointer is aligned")
tried to align the stack pointer in show_trace_log_lvl(), otherwise the
"stack < stack_info.end" check can't guarantee that the last read does
not go past the end of the stack.

However, we have the same problem with the initial value of the stack
pointer, it can also be unaligned. So without this patch this trivial
kernel module

	#include <linux/module.h>

	static int init(void)
	{
		asm volatile("sub    $0x4,%rsp");
		dump_stack();
		asm volatile("add    $0x4,%rsp");

		return -EAGAIN;
	}

	module_init(init);
	MODULE_LICENSE("GPL");

crashes the kernel.

Fixes: e335bb51cc ("x86/unwind: Ensure stack pointer is aligned")
Signed-off-by: Vernon Lovejoy <vlovejoy@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20230512104232.GA10227@redhat.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vernon Lovejoy 2023-05-12 12:42:32 +02:00 committed by Greg Kroah-Hartman
parent c84733a53f
commit 5326b73f64
1 changed files with 5 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
arch/x86/kernel/dumpstack.c
View file

@ -115,7 +115,6 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
printk("%sCall Trace:\n", log_lvl);
unwind_start(&state, task, regs, stack);
stack = stack ? : get_stack_pointer(task, regs);
regs = unwind_get_entry_regs(&state, &partial);
/*
@ -134,9 +133,13 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
* - hardirq stack
* - entry stack
*/
for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
for (stack = stack ?: get_stack_pointer(task, regs);
stack;
stack = stack_info.next_sp) {
const char *stack_name;
stack = PTR_ALIGN(stack, sizeof(long));
if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
/*
* We weren't on a valid stack. It's possible that