android/android_kernel_samsung_sm8650
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86/show_trace_log_lvl: Ensure stack pointer is aligned, again

Browse Source 
commit 2e4be0d011f21593c6b316806779ba1eba2cd7e0 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 a7edc86e14
commit d8cfe5ccc9
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

@ -195,7 +195,6 @@ static 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);
/*
@ -214,9 +213,13 @@ static 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