From d11c2a0de2824395656cf8ed15811580c9dd38aa Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sat, 28 May 2016 21:21:31 -0700 Subject: [PATCH] sparc: Harden signal return frame checks. All signal frames must be at least 16-byte aligned, because that is the alignment we explicitly create when we build signal return stack frames. All stack pointers must be at least 8-byte aligned. Signed-off-by: David S. Miller --- arch/sparc/kernel/signal32.c | 46 ++++++++++++++++++++++------------ arch/sparc/kernel/signal_32.c | 41 +++++++++++++++++++----------- arch/sparc/kernel/signal_64.c | 31 +++++++++++++++-------- arch/sparc/kernel/sigutil_32.c | 9 ++++++- arch/sparc/kernel/sigutil_64.c | 10 ++++++-- 5 files changed, 92 insertions(+), 45 deletions(-) diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c index 3c25241fa5cb..91cc2f4ae4d9 100644 --- a/arch/sparc/kernel/signal32.c +++ b/arch/sparc/kernel/signal32.c @@ -138,12 +138,24 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from) return 0; } +/* Checks if the fp is valid. We always build signal frames which are + * 16-byte aligned, therefore we can always enforce that the restore + * frame has that property as well. + */ +static bool invalid_frame_pointer(void __user *fp, int fplen) +{ + if ((((unsigned long) fp) & 15) || + ((unsigned long)fp) > 0x100000000ULL - fplen) + return true; + return false; +} + void do_sigreturn32(struct pt_regs *regs) { struct signal_frame32 __user *sf; compat_uptr_t fpu_save; compat_uptr_t rwin_save; - unsigned int psr; + unsigned int psr, ufp; unsigned int pc, npc; sigset_t set; compat_sigset_t seta; @@ -158,11 +170,16 @@ void do_sigreturn32(struct pt_regs *regs) sf = (struct signal_frame32 __user *) regs->u_regs[UREG_FP]; /* 1. Make sure we are not getting garbage from the user */ - if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) || - (((unsigned long) sf) & 3)) + if (invalid_frame_pointer(sf, sizeof(*sf))) + goto segv; + + if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP])) + goto segv; + + if (ufp & 0x7) goto segv; - if (get_user(pc, &sf->info.si_regs.pc) || + if (__get_user(pc, &sf->info.si_regs.pc) || __get_user(npc, &sf->info.si_regs.npc)) goto segv; @@ -227,7 +244,7 @@ segv: asmlinkage void do_rt_sigreturn32(struct pt_regs *regs) { struct rt_signal_frame32 __user *sf; - unsigned int psr, pc, npc; + unsigned int psr, pc, npc, ufp; compat_uptr_t fpu_save; compat_uptr_t rwin_save; sigset_t set; @@ -242,11 +259,16 @@ asmlinkage void do_rt_sigreturn32(struct pt_regs *regs) sf = (struct rt_signal_frame32 __user *) regs->u_regs[UREG_FP]; /* 1. Make sure we are not getting garbage from the user */ - if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) || - (((unsigned long) sf) & 3)) + if (invalid_frame_pointer(sf, sizeof(*sf))) goto segv; - if (get_user(pc, &sf->regs.pc) || + if (get_user(ufp, &sf->regs.u_regs[UREG_FP])) + goto segv; + + if (ufp & 0x7) + goto segv; + + if (__get_user(pc, &sf->regs.pc) || __get_user(npc, &sf->regs.npc)) goto segv; @@ -307,14 +329,6 @@ segv: force_sig(SIGSEGV, current); } -/* Checks if the fp is valid */ -static int invalid_frame_pointer(void __user *fp, int fplen) -{ - if ((((unsigned long) fp) & 7) || ((unsigned long)fp) > 0x100000000ULL - fplen) - return 1; - return 0; -} - static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize) { unsigned long sp; diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c index 52aa5e4ce5e7..c3c12efe0bc0 100644 --- a/arch/sparc/kernel/signal_32.c +++ b/arch/sparc/kernel/signal_32.c @@ -60,10 +60,22 @@ struct rt_signal_frame { #define SF_ALIGNEDSZ (((sizeof(struct signal_frame) + 7) & (~7))) #define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame) + 7) & (~7))) +/* Checks if the fp is valid. We always build signal frames which are + * 16-byte aligned, therefore we can always enforce that the restore + * frame has that property as well. + */ +static inline bool invalid_frame_pointer(void __user *fp, int fplen) +{ + if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen)) + return true; + + return false; +} + asmlinkage void do_sigreturn(struct pt_regs *regs) { + unsigned long up_psr, pc, npc, ufp; struct signal_frame __user *sf; - unsigned long up_psr, pc, npc; sigset_t set; __siginfo_fpu_t __user *fpu_save; __siginfo_rwin_t __user *rwin_save; @@ -77,10 +89,13 @@ asmlinkage void do_sigreturn(struct pt_regs *regs) sf = (struct signal_frame __user *) regs->u_regs[UREG_FP]; /* 1. Make sure we are not getting garbage from the user */ - if (!access_ok(VERIFY_READ, sf, sizeof(*sf))) + if (!invalid_frame_pointer(sf, sizeof(*sf))) + goto segv_and_exit; + + if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP])) goto segv_and_exit; - if (((unsigned long) sf) & 3) + if (ufp & 0x7) goto segv_and_exit; err = __get_user(pc, &sf->info.si_regs.pc); @@ -127,7 +142,7 @@ segv_and_exit: asmlinkage void do_rt_sigreturn(struct pt_regs *regs) { struct rt_signal_frame __user *sf; - unsigned int psr, pc, npc; + unsigned int psr, pc, npc, ufp; __siginfo_fpu_t __user *fpu_save; __siginfo_rwin_t __user *rwin_save; sigset_t set; @@ -135,8 +150,13 @@ asmlinkage void do_rt_sigreturn(struct pt_regs *regs) synchronize_user_stack(); sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP]; - if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) || - (((unsigned long) sf) & 0x03)) + if (!invalid_frame_pointer(sf, sizeof(*sf))) + goto segv; + + if (get_user(ufp, &sf->regs.u_regs[UREG_FP])) + goto segv; + + if (ufp & 0x7) goto segv; err = __get_user(pc, &sf->regs.pc); @@ -178,15 +198,6 @@ segv: force_sig(SIGSEGV, current); } -/* Checks if the fp is valid */ -static inline int invalid_frame_pointer(void __user *fp, int fplen) -{ - if ((((unsigned long) fp) & 7) || !__access_ok((unsigned long)fp, fplen)) - return 1; - - return 0; -} - static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize) { unsigned long sp = regs->u_regs[UREG_FP]; diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c index 39aaec173f66..5ee930c48f4c 100644 --- a/arch/sparc/kernel/signal_64.c +++ b/arch/sparc/kernel/signal_64.c @@ -234,6 +234,17 @@ do_sigsegv: goto out; } +/* Checks if the fp is valid. We always build rt signal frames which + * are 16-byte aligned, therefore we can always enforce that the + * restore frame has that property as well. + */ +static bool invalid_frame_pointer(void __user *fp) +{ + if (((unsigned long) fp) & 15) + return true; + return false; +} + struct rt_signal_frame { struct sparc_stackf ss; siginfo_t info; @@ -246,8 +257,8 @@ struct rt_signal_frame { void do_rt_sigreturn(struct pt_regs *regs) { + unsigned long tpc, tnpc, tstate, ufp; struct rt_signal_frame __user *sf; - unsigned long tpc, tnpc, tstate; __siginfo_fpu_t __user *fpu_save; __siginfo_rwin_t __user *rwin_save; sigset_t set; @@ -261,10 +272,16 @@ void do_rt_sigreturn(struct pt_regs *regs) (regs->u_regs [UREG_FP] + STACK_BIAS); /* 1. Make sure we are not getting garbage from the user */ - if (((unsigned long) sf) & 3) + if (invalid_frame_pointer(sf)) + goto segv; + + if (get_user(ufp, &sf->regs.u_regs[UREG_FP])) goto segv; - err = get_user(tpc, &sf->regs.tpc); + if ((ufp + STACK_BIAS) & 0x7) + goto segv; + + err = __get_user(tpc, &sf->regs.tpc); err |= __get_user(tnpc, &sf->regs.tnpc); if (test_thread_flag(TIF_32BIT)) { tpc &= 0xffffffff; @@ -308,14 +325,6 @@ segv: force_sig(SIGSEGV, current); } -/* Checks if the fp is valid */ -static int invalid_frame_pointer(void __user *fp) -{ - if (((unsigned long) fp) & 15) - return 1; - return 0; -} - static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize) { unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS; diff --git a/arch/sparc/kernel/sigutil_32.c b/arch/sparc/kernel/sigutil_32.c index 0f6eebe71e6c..e5fe8cef9a69 100644 --- a/arch/sparc/kernel/sigutil_32.c +++ b/arch/sparc/kernel/sigutil_32.c @@ -48,6 +48,10 @@ int save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu) int restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu) { int err; + + if (((unsigned long) fpu) & 3) + return -EFAULT; + #ifdef CONFIG_SMP if (test_tsk_thread_flag(current, TIF_USEDFPU)) regs->psr &= ~PSR_EF; @@ -97,7 +101,10 @@ int restore_rwin_state(__siginfo_rwin_t __user *rp) struct thread_info *t = current_thread_info(); int i, wsaved, err; - __get_user(wsaved, &rp->wsaved); + if (((unsigned long) rp) & 3) + return -EFAULT; + + get_user(wsaved, &rp->wsaved); if (wsaved > NSWINS) return -EFAULT; diff --git a/arch/sparc/kernel/sigutil_64.c b/arch/sparc/kernel/sigutil_64.c index 387834a9c56a..36aadcbeac69 100644 --- a/arch/sparc/kernel/sigutil_64.c +++ b/arch/sparc/kernel/sigutil_64.c @@ -37,7 +37,10 @@ int restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu) unsigned long fprs; int err; - err = __get_user(fprs, &fpu->si_fprs); + if (((unsigned long) fpu) & 7) + return -EFAULT; + + err = get_user(fprs, &fpu->si_fprs); fprs_write(0); regs->tstate &= ~TSTATE_PEF; if (fprs & FPRS_DL) @@ -72,7 +75,10 @@ int restore_rwin_state(__siginfo_rwin_t __user *rp) struct thread_info *t = current_thread_info(); int i, wsaved, err; - __get_user(wsaved, &rp->wsaved); + if (((unsigned long) rp) & 7) + return -EFAULT; + + get_user(wsaved, &rp->wsaved); if (wsaved > NSWINS) return -EFAULT; -- 2.20.1