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

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
......@@ -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.
......
......@@ -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)
......
......@@ -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
......
......@@ -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
......
......@@ -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)
......
......@@ -550,23 +550,26 @@ static int handle_signal(unsigned long sig, siginfo_t *info,
struct mips_abi *abi = current->thread.abi;
void *vdso = current->mm->context.vdso;
switch(regs->regs[0]) {
case ERESTART_RESTARTBLOCK:
case ERESTARTNOHAND:
regs->regs[2] = EINTR;
break;
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
if (regs->regs[0]) {
switch(regs->regs[2]) {
case ERESTART_RESTARTBLOCK:
case ERESTARTNOHAND:
regs->regs[2] = EINTR;
break;
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->regs[2] = EINTR;
break;
}
/* fallthrough */
case ERESTARTNOINTR:
regs->regs[7] = regs->regs[26];
regs->regs[2] = regs->regs[0];
regs->cp0_epc -= 4;
}
/* fallthrough */
case ERESTARTNOINTR: /* Userland will reload $v0. */
regs->regs[7] = regs->regs[26];
regs->cp0_epc -= 8;
}
regs->regs[0] = 0; /* Don't deal with this again. */
regs->regs[0] = 0; /* Don't deal with this again. */
}
if (sig_uses_siginfo(ka))
ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
......@@ -625,17 +628,13 @@ static void do_signal(struct pt_regs *regs)
return;
}
/*
* Who's code doesn't conform to the restartable syscall convention
* dies here!!! The li instruction, a single machine instruction,
* must directly be followed by the syscall instruction.
*/
if (regs->regs[0]) {
if (regs->regs[2] == ERESTARTNOHAND ||
regs->regs[2] == ERESTARTSYS ||
regs->regs[2] == ERESTARTNOINTR) {
regs->regs[2] = regs->regs[0];
regs->regs[7] = regs->regs[26];
regs->cp0_epc -= 8;
regs->cp0_epc -= 4;
}
if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
regs->regs[2] = current->thread.abi->restart;
......
......@@ -109,8 +109,6 @@ static void emulate_load_store_insn(struct pt_regs *regs,
unsigned long value;
unsigned int res;
regs->regs[0] = 0;
/*
* This load never faults.
*/
......
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