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Commit 8f5a00eb authored by Al Viro's avatar Al Viro Committed by Ralf Baechle
Browse files

MIPS: Sanitize restart logics 



Put the original syscall number into ->regs[0] when we leave syscall
with error.  Use it in restart logics.  Everything else will have
it 0 since we pass through SAVE_SOME on all the ways in.  Note that
in places like bad_stack and inllegal_syscall we leave it 0 - it's not
restartable.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1698/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent e5b377a8

arch/mips/kernel/branch.c

+0 −1
Original line number Diff line number Diff line
@@ -40,7 +40,6 @@ int __compute_return_epc(struct pt_regs *regs) 
		return -EFAULT;

	}



	regs->regs[0] = 0;

	switch (insn.i_format.opcode) {

	/*

	 * jr and jalr are in r_format format.

arch/mips/kernel/scall32-o32.S

+4 −5
Original line number Diff line number Diff line
@@ -63,9 +63,9 @@ stack_done: 
	sw	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	lw	t1, PT_R2(sp)		# syscall number

	negu	v0			# error

	sw	v0, PT_R0(sp)		# set flag for syscall

					# restarting

	sw	t1, PT_R0(sp)		# save it for syscall restarting

1:	sw	v0, PT_R2(sp)		# result



o32_syscall_exit:
@@ -104,9 +104,9 @@ syscall_trace_entry: 
	sw	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	lw	t1, PT_R2(sp)		# syscall number

	negu	v0			# error

	sw	v0, PT_R0(sp)		# set flag for syscall

					# restarting

	sw	t1, PT_R0(sp)		# save it for syscall restarting

1:	sw	v0, PT_R2(sp)		# result



	j	syscall_exit
@@ -170,7 +170,6 @@ stackargs: 
	 */

bad_stack:

	negu	v0				# error

	sw	v0, PT_R0(sp)

	sw	v0, PT_R2(sp)

	li	t0, 1				# set error flag

	sw	t0, PT_R7(sp)

arch/mips/kernel/scall64-64.S

+4 −3
Original line number Diff line number Diff line
@@ -66,9 +66,9 @@ NESTED(handle_sys64, PT_SIZE, sp) 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# set flag for syscall

					# restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



n64_syscall_exit:
@@ -109,8 +109,9 @@ syscall_trace_entry: 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# set flag for syscall restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



	j	syscall_exit

arch/mips/kernel/scall64-n32.S

+4 −2
Original line number Diff line number Diff line
@@ -65,8 +65,9 @@ NESTED(handle_sysn32, PT_SIZE, sp) 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# set flag for syscall restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



	local_irq_disable		# make sure need_resched and
@@ -106,8 +107,9 @@ n32_syscall_trace_entry: 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# set flag for syscall restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



	j	syscall_exit

arch/mips/kernel/scall64-o32.S

+4 −3
Original line number Diff line number Diff line
@@ -93,8 +93,9 @@ NESTED(handle_sys, PT_SIZE, sp) 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# flag for syscall restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



o32_syscall_exit:
@@ -142,8 +143,9 @@ trace_a_syscall: 
	sd	t0, PT_R7(sp)		# set error flag

	beqz	t0, 1f



	ld	t1, PT_R2(sp)		# syscall number

	dnegu	v0			# error

	sd	v0, PT_R0(sp)		# set flag for syscall restarting

	sd	t1, PT_R0(sp)		# save it for syscall restarting

1:	sd	v0, PT_R2(sp)		# result



	j	syscall_exit
@@ -155,7 +157,6 @@ trace_a_syscall: 
	 */

bad_stack:

	dnegu	v0			# error

	sd	v0, PT_R0(sp)

	sd	v0, PT_R2(sp)

	li	t0, 1			# set error flag

	sd	t0, PT_R7(sp)