From 978727ca331ebd8b479f6a7afd27bb2e6504b2e3 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 15 Feb 2020 12:23:36 -0500 Subject: [PATCH] x86: get rid of get_user_ex() in ia32_restore_sigcontext() Just do copyin into a local struct and be done with that - we are on a shallow stack here. [reworked by tglx, removing the macro horrors while we are touching that] Signed-off-by: Al Viro --- arch/x86/ia32/ia32_signal.c | 106 ++++++++++++++++++-------------------------- 1 file changed, 44 insertions(+), 62 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index c72025d615f8..23e2c55d8a59 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -36,70 +36,56 @@ #include #include +static inline void reload_segments(struct sigcontext_32 *sc) +{ + unsigned int cur; + + savesegment(gs, cur); + if ((sc->gs | 0x03) != cur) + load_gs_index(sc->gs | 0x03); + savesegment(fs, cur); + if ((sc->fs | 0x03) != cur) + loadsegment(fs, sc->fs | 0x03); + savesegment(ds, cur); + if ((sc->ds | 0x03) != cur) + loadsegment(ds, sc->ds | 0x03); + savesegment(es, cur); + if ((sc->es | 0x03) != cur) + loadsegment(es, sc->es | 0x03); +} + /* * Do a signal return; undo the signal stack. */ -#define loadsegment_gs(v) load_gs_index(v) -#define loadsegment_fs(v) loadsegment(fs, v) -#define loadsegment_ds(v) loadsegment(ds, v) -#define loadsegment_es(v) loadsegment(es, v) - -#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; }) -#define set_user_seg(seg, v) loadsegment_##seg(v) - -#define COPY(x) { \ - get_user_ex(regs->x, &sc->x); \ -} - -#define GET_SEG(seg) ({ \ - unsigned short tmp; \ - get_user_ex(tmp, &sc->seg); \ - tmp; \ -}) - -#define COPY_SEG_CPL3(seg) do { \ - regs->seg = GET_SEG(seg) | 3; \ -} while (0) - -#define RELOAD_SEG(seg) { \ - unsigned int pre = (seg) | 3; \ - unsigned int cur = get_user_seg(seg); \ - if (pre != cur) \ - set_user_seg(seg, pre); \ -} - static int ia32_restore_sigcontext(struct pt_regs *regs, - struct sigcontext_32 __user *sc) + struct sigcontext_32 __user *usc) { - unsigned int tmpflags, err = 0; - u16 gs, fs, es, ds; - void __user *buf; - u32 tmp; + struct sigcontext_32 sc; /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; - get_user_try { - gs = GET_SEG(gs); - fs = GET_SEG(fs); - ds = GET_SEG(ds); - es = GET_SEG(es); - - COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); - COPY(dx); COPY(cx); COPY(ip); COPY(ax); - /* Don't touch extended registers */ - - COPY_SEG_CPL3(cs); - COPY_SEG_CPL3(ss); - - get_user_ex(tmpflags, &sc->flags); - regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); - /* disable syscall checks */ - regs->orig_ax = -1; + if (unlikely(copy_from_user(&sc, usc, sizeof(sc)))) + return -EFAULT; - get_user_ex(tmp, &sc->fpstate); - buf = compat_ptr(tmp); - } get_user_catch(err); + /* Get only the ia32 registers. */ + regs->bx = sc.bx; + regs->cx = sc.cx; + regs->dx = sc.dx; + regs->si = sc.si; + regs->di = sc.di; + regs->bp = sc.bp; + regs->ax = sc.ax; + regs->sp = sc.sp; + regs->ip = sc.ip; + + /* Get CS/SS and force CPL3 */ + regs->cs = sc.cs | 0x03; + regs->ss = sc.ss | 0x03; + + regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS); + /* disable syscall checks */ + regs->orig_ax = -1; /* * Reload fs and gs if they have changed in the signal @@ -107,14 +93,8 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, * the handler, but does not clobber them at least in the * normal case. */ - RELOAD_SEG(gs); - RELOAD_SEG(fs); - RELOAD_SEG(ds); - RELOAD_SEG(es); - - err |= fpu__restore_sig(buf, 1); - - return err; + reload_segments(&sc); + return fpu__restore_sig(compat_ptr(sc.fpstate), 1); } COMPAT_SYSCALL_DEFINE0(sigreturn) @@ -172,6 +152,8 @@ badframe: * Set up a signal frame. */ +#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) -- 2.11.0