From 44a1d996325982025eefcdc50b636ab83e813372 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 15 Feb 2020 18:46:02 -0500 Subject: [PATCH] x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers What's left is just a sequence of stores to userland addresses, with all error handling, etc. done out of line. Calling that from user_access block is safe, but rather than teaching objtool to recognize it as such we can just make it always_inline - it is small enough and has few enough callers, for the space savings not to be an issue. Rename the sucker to __unsafe_setup_sigcontext32() and provide unsafe_put_sigcontext32() with usual kind of semantics. Signed-off-by: Al Viro --- arch/x86/ia32/ia32_signal.c | 44 +++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 16 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index a96995aa23da..799ca5b31b87 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -154,13 +154,11 @@ badframe: #define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; }) -static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc, - void __user *fpstate, - struct pt_regs *regs, unsigned int mask) +static __always_inline int +__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc, + void __user *fpstate, + struct pt_regs *regs, unsigned int mask) { - if (!user_access_begin(sc, sizeof(struct sigcontext_32))) - return -EFAULT; - unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault); unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault); unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault); @@ -187,13 +185,18 @@ static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc, /* non-iBCS2 extensions.. */ unsafe_put_user(mask, &sc->oldmask, Efault); unsafe_put_user(current->thread.cr2, &sc->cr2, Efault); - user_access_end(); return 0; + Efault: - user_access_end(); return -EFAULT; } +#define unsafe_put_sigcontext32(sc, fp, regs, set, label) \ +do { \ + if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0])) \ + goto label; \ +} while(0) + /* * Determine which stack to use.. */ @@ -234,7 +237,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig, struct sigframe_ia32 __user *frame; void __user *restorer; int err = 0; - void __user *fpstate = NULL; + void __user *fp = NULL; /* copy_to_user optimizes that into a single 8 byte store */ static const struct { @@ -247,7 +250,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig, 0x80cd, /* int $0x80 */ }; - frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate); + frame = get_sigframe(ksig, regs, sizeof(*frame), &fp); if (!access_ok(frame, sizeof(*frame))) return -EFAULT; @@ -255,9 +258,12 @@ int ia32_setup_frame(int sig, struct ksignal *ksig, if (__put_user(sig, &frame->sig)) return -EFAULT; - if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0])) + if (!user_access_begin(&frame->sc, sizeof(struct sigcontext_32))) return -EFAULT; + unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault); + user_access_end(); + if (__put_user(set->sig[1], &frame->extramask[0])) return -EFAULT; @@ -301,6 +307,9 @@ int ia32_setup_frame(int sig, struct ksignal *ksig, regs->ss = __USER32_DS; return 0; +Efault: + user_access_end(); + return -EFAULT; } int ia32_setup_rt_frame(int sig, struct ksignal *ksig, @@ -309,7 +318,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, struct rt_sigframe_ia32 __user *frame; void __user *restorer; int err = 0; - void __user *fpstate = NULL; + void __user *fp = NULL; /* __copy_to_user optimizes that into a single 8 byte store */ static const struct { @@ -324,7 +333,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, 0, }; - frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate); + frame = get_sigframe(ksig, regs, sizeof(*frame), &fp); if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; @@ -355,9 +364,12 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault); user_access_end(); - err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false); - err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate, - regs, set->sig[0]); + if (__copy_siginfo_to_user32(&frame->info, &ksig->info, false)) + return -EFAULT; + if (!user_access_begin(&frame->uc.uc_mcontext, sizeof(struct sigcontext_32))) + return -EFAULT; + unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault); + user_access_end(); err |= __put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask); if (err)