From 8f5a00eb422ed86e77bb8f67e08b9fe6d30f679a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 28 Sep 2010 18:50:37 +0100 Subject: [PATCH] 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: Al Viro 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: Ralf Baechle --- arch/mips/kernel/branch.c | 1 - arch/mips/kernel/scall32-o32.S | 9 ++++----- arch/mips/kernel/scall64-64.S | 7 ++++--- arch/mips/kernel/scall64-n32.S | 6 ++++-- arch/mips/kernel/scall64-o32.S | 7 ++++--- arch/mips/kernel/signal.c | 37 +++++++++++++++++----------------- arch/mips/kernel/unaligned.c | 2 -- 7 files changed, 34 insertions(+), 35 deletions(-) diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c index 0176ed015c89..32103cc2a257 100644 --- a/arch/mips/kernel/branch.c +++ b/arch/mips/kernel/branch.c @@ -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. diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S index 17202bbe843f..73a061e85531 100644 --- a/arch/mips/kernel/scall32-o32.S +++ b/arch/mips/kernel/scall32-o32.S @@ -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) diff --git a/arch/mips/kernel/scall64-64.S b/arch/mips/kernel/scall64-64.S index a8a6c596eb04..eb0bb73172c3 100644 --- a/arch/mips/kernel/scall64-64.S +++ b/arch/mips/kernel/scall64-64.S @@ -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 diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S index a3d66137731a..4da3fafaa313 100644 --- a/arch/mips/kernel/scall64-n32.S +++ b/arch/mips/kernel/scall64-n32.S @@ -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 diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S index 813689ef2384..7ce0a3685627 100644 --- a/arch/mips/kernel/scall64-o32.S +++ b/arch/mips/kernel/scall64-o32.S @@ -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) diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c index b3273aeaeedc..604f077bb5bf 100644 --- a/arch/mips/kernel/signal.c +++ b/arch/mips/kernel/signal.c @@ -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; diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c index 69b039ca8d83..33d5a5ce4a29 100644 --- a/arch/mips/kernel/unaligned.c +++ b/arch/mips/kernel/unaligned.c @@ -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. */ -- 2.30.2