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Commit 43efb3f0 authored by Jiaxun Yang's avatar Jiaxun Yang Committed by Greg Kroah-Hartman
Browse files

MIPS: scall: Save thread_info.syscall unconditionally on entry 



[ Upstream commit 4370b673ccf240bf7587b0cb8e6726a5ccaf1f17 ]

thread_info.syscall is used by syscall_get_nr to supply syscall nr
over a thread stack frame.

Previously, thread_info.syscall is only saved at syscall_trace_enter
when syscall tracing is enabled. However rest of the kernel code do
expect syscall_get_nr to be available without syscall tracing. The
previous design breaks collect_syscall.

Move saving process to syscall entry to fix it.

Reported-by: default avatarXi Ruoyao <xry111@xry111.site>
Link: https://github.com/util-linux/util-linux/issues/2867


Signed-off-by: default avatarJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 2cd614ba

arch/mips/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -157,7 +157,7 @@ static inline long regs_return_value(struct pt_regs *regs) 
#define instruction_pointer(regs) ((regs)->cp0_epc)

#define profile_pc(regs) instruction_pointer(regs)



extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall);

extern asmlinkage long syscall_trace_enter(struct pt_regs *regs);

extern asmlinkage void syscall_trace_leave(struct pt_regs *regs);



extern void die(const char *, struct pt_regs *) __noreturn;

arch/mips/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ void output_thread_info_defines(void) 
	OFFSET(TI_PRE_COUNT, thread_info, preempt_count);

	OFFSET(TI_ADDR_LIMIT, thread_info, addr_limit);

	OFFSET(TI_REGS, thread_info, regs);

	OFFSET(TI_SYSCALL, thread_info, syscall);

	DEFINE(_THREAD_SIZE, THREAD_SIZE);

	DEFINE(_THREAD_MASK, THREAD_MASK);

	DEFINE(_IRQ_STACK_SIZE, IRQ_STACK_SIZE);

arch/mips/kernel/ptrace.c

+6 −9
Original line number Diff line number Diff line
@@ -1399,16 +1399,13 @@ long arch_ptrace(struct task_struct *child, long request, 
 * Notification of system call entry/exit

 * - triggered by current->work.syscall_trace

 */

asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)

asmlinkage long syscall_trace_enter(struct pt_regs *regs)

{

	user_exit();



	current_thread_info()->syscall = syscall;



	if (test_thread_flag(TIF_SYSCALL_TRACE)) {

		if (tracehook_report_syscall_entry(regs))

			return -1;

		syscall = current_thread_info()->syscall;

	}



#ifdef CONFIG_SECCOMP
@@ -1417,7 +1414,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall) 
		struct seccomp_data sd;

		unsigned long args[6];



		sd.nr = syscall;

		sd.nr = current_thread_info()->syscall;

		sd.arch = syscall_get_arch(current);

		syscall_get_arguments(current, regs, args);

		for (i = 0; i < 6; i++)
@@ -1427,23 +1424,23 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall) 
		ret = __secure_computing(&sd);

		if (ret == -1)

			return ret;

		syscall = current_thread_info()->syscall;

	}

#endif



	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))

		trace_sys_enter(regs, regs->regs[2]);



	audit_syscall_entry(syscall, regs->regs[4], regs->regs[5],

	audit_syscall_entry(current_thread_info()->syscall,

			    regs->regs[4], regs->regs[5],

			    regs->regs[6], regs->regs[7]);



	/*

	 * Negative syscall numbers are mistaken for rejected syscalls, but

	 * won't have had the return value set appropriately, so we do so now.

	 */

	if (syscall < 0)

	if (current_thread_info()->syscall < 0)

		syscall_set_return_value(current, regs, -ENOSYS, 0);

	return syscall;

	return current_thread_info()->syscall;

}



/*

arch/mips/kernel/scall32-o32.S

+13 −10
Original line number Diff line number Diff line
@@ -80,6 +80,18 @@ loads_done: 
	PTR	load_a7, bad_stack_a7

	.previous



	/*

	 * syscall number is in v0 unless we called syscall(__NR_###)

	 * where the real syscall number is in a0

	 */

	subu	t2, v0,  __NR_O32_Linux

	bnez	t2, 1f /* __NR_syscall at offset 0 */

	LONG_S	a0, TI_SYSCALL($28)	# Save a0 as syscall number

	b	2f

1:

	LONG_S	v0, TI_SYSCALL($28)	# Save v0 as syscall number

2:



	lw	t0, TI_FLAGS($28)	# syscall tracing enabled?

	li	t1, _TIF_WORK_SYSCALL_ENTRY

	and	t0, t1
@@ -117,16 +129,7 @@ syscall_trace_entry: 
	SAVE_STATIC

	move	a0, sp



	/*

	 * syscall number is in v0 unless we called syscall(__NR_###)

	 * where the real syscall number is in a0

	 */

	move	a1, v0

	subu	t2, v0,  __NR_O32_Linux

	bnez	t2, 1f /* __NR_syscall at offset 0 */

	lw	a1, PT_R4(sp)



1:	jal	syscall_trace_enter

	jal	syscall_trace_enter



	bltz	v0, 1f			# seccomp failed? Skip syscall

arch/mips/kernel/scall64-n32.S

+2 −1
Original line number Diff line number Diff line
@@ -44,6 +44,8 @@ NESTED(handle_sysn32, PT_SIZE, sp) 


	sd	a3, PT_R26(sp)		# save a3 for syscall restarting



	LONG_S	v0, TI_SYSCALL($28)     # Store syscall number



	li	t1, _TIF_WORK_SYSCALL_ENTRY

	LONG_L	t0, TI_FLAGS($28)	# syscall tracing enabled?

	and	t0, t1, t0
@@ -72,7 +74,6 @@ syscall_common: 
n32_syscall_trace_entry:

	SAVE_STATIC

	move	a0, sp

	move	a1, v0

	jal	syscall_trace_enter



	bltz	v0, 1f			# seccomp failed? Skip syscall