All of lore.kernel.org
 help / color / mirror / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
	Michael Schmitz <schmitzmic@gmail.com>,
	Finn Thain <fthain@linux-m68k.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 05/12] m68k: Handle arrivals of multiple signals correctly
Date: Thu, 14 Oct 2021 16:54:05 +0200	[thread overview]
Message-ID: <20211014145206.732488174@linuxfoundation.org> (raw)
In-Reply-To: <20211014145206.566123760@linuxfoundation.org>

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 4bb0bd81ce5e97092dfda6a106d414b703ec0ee8 ]

When we have several pending signals, have entered with the kernel
with large exception frame *and* have already built at least one
sigframe, regs->stkadj is going to be non-zero and regs->format/sr/pc
are going to be junk - the real values are in shifted exception stack
frame we'd built when putting together the first sigframe.

If that happens, subsequent sigframes are going to be garbage.
Not hard to fix - just need to find the "adjusted" frame first
and look for format/vector/sr/pc in it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Tested-by: Finn Thain <fthain@linux-m68k.org>
Link: https://lore.kernel.org/r/YP2dBIAPTaVvHiZ6@zeniv-ca.linux.org.uk
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/m68k/kernel/signal.c | 88 +++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 46 deletions(-)

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index 72850b85ecf8..c67a68b6b69d 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -448,7 +448,7 @@ static inline void save_fpu_state(struct sigcontext *sc, struct pt_regs *regs)
 
 	if (CPU_IS_060 ? sc->sc_fpstate[2] : sc->sc_fpstate[0]) {
 		fpu_version = sc->sc_fpstate[0];
-		if (CPU_IS_020_OR_030 &&
+		if (CPU_IS_020_OR_030 && !regs->stkadj &&
 		    regs->vector >= (VEC_FPBRUC * 4) &&
 		    regs->vector <= (VEC_FPNAN * 4)) {
 			/* Clear pending exception in 68882 idle frame */
@@ -511,7 +511,7 @@ static inline int rt_save_fpu_state(struct ucontext __user *uc, struct pt_regs *
 		if (!(CPU_IS_060 || CPU_IS_COLDFIRE))
 			context_size = fpstate[1];
 		fpu_version = fpstate[0];
-		if (CPU_IS_020_OR_030 &&
+		if (CPU_IS_020_OR_030 && !regs->stkadj &&
 		    regs->vector >= (VEC_FPBRUC * 4) &&
 		    regs->vector <= (VEC_FPNAN * 4)) {
 			/* Clear pending exception in 68882 idle frame */
@@ -828,18 +828,24 @@ badframe:
 	return 0;
 }
 
+static inline struct pt_regs *rte_regs(struct pt_regs *regs)
+{
+	return (void *)regs + regs->stkadj;
+}
+
 static void setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
 			     unsigned long mask)
 {
+	struct pt_regs *tregs = rte_regs(regs);
 	sc->sc_mask = mask;
 	sc->sc_usp = rdusp();
 	sc->sc_d0 = regs->d0;
 	sc->sc_d1 = regs->d1;
 	sc->sc_a0 = regs->a0;
 	sc->sc_a1 = regs->a1;
-	sc->sc_sr = regs->sr;
-	sc->sc_pc = regs->pc;
-	sc->sc_formatvec = regs->format << 12 | regs->vector;
+	sc->sc_sr = tregs->sr;
+	sc->sc_pc = tregs->pc;
+	sc->sc_formatvec = tregs->format << 12 | tregs->vector;
 	save_a5_state(sc, regs);
 	save_fpu_state(sc, regs);
 }
@@ -847,6 +853,7 @@ static void setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
 static inline int rt_setup_ucontext(struct ucontext __user *uc, struct pt_regs *regs)
 {
 	struct switch_stack *sw = (struct switch_stack *)regs - 1;
+	struct pt_regs *tregs = rte_regs(regs);
 	greg_t __user *gregs = uc->uc_mcontext.gregs;
 	int err = 0;
 
@@ -867,9 +874,9 @@ static inline int rt_setup_ucontext(struct ucontext __user *uc, struct pt_regs *
 	err |= __put_user(sw->a5, &gregs[13]);
 	err |= __put_user(sw->a6, &gregs[14]);
 	err |= __put_user(rdusp(), &gregs[15]);
-	err |= __put_user(regs->pc, &gregs[16]);
-	err |= __put_user(regs->sr, &gregs[17]);
-	err |= __put_user((regs->format << 12) | regs->vector, &uc->uc_formatvec);
+	err |= __put_user(tregs->pc, &gregs[16]);
+	err |= __put_user(tregs->sr, &gregs[17]);
+	err |= __put_user((tregs->format << 12) | tregs->vector, &uc->uc_formatvec);
 	err |= rt_save_fpu_state(uc, regs);
 	return err;
 }
@@ -886,13 +893,14 @@ static int setup_frame(struct ksignal *ksig, sigset_t *set,
 			struct pt_regs *regs)
 {
 	struct sigframe __user *frame;
-	int fsize = frame_extra_sizes(regs->format);
+	struct pt_regs *tregs = rte_regs(regs);
+	int fsize = frame_extra_sizes(tregs->format);
 	struct sigcontext context;
 	int err = 0, sig = ksig->sig;
 
 	if (fsize < 0) {
 		pr_debug("setup_frame: Unknown frame format %#x\n",
-			 regs->format);
+			 tregs->format);
 		return -EFAULT;
 	}
 
@@ -903,7 +911,7 @@ static int setup_frame(struct ksignal *ksig, sigset_t *set,
 
 	err |= __put_user(sig, &frame->sig);
 
-	err |= __put_user(regs->vector, &frame->code);
+	err |= __put_user(tregs->vector, &frame->code);
 	err |= __put_user(&frame->sc, &frame->psc);
 
 	if (_NSIG_WORDS > 1)
@@ -928,34 +936,28 @@ static int setup_frame(struct ksignal *ksig, sigset_t *set,
 
 	push_cache ((unsigned long) &frame->retcode);
 
-	/*
-	 * Set up registers for signal handler.  All the state we are about
-	 * to destroy is successfully copied to sigframe.
-	 */
-	wrusp ((unsigned long) frame);
-	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
-	adjustformat(regs);
-
 	/*
 	 * This is subtle; if we build more than one sigframe, all but the
 	 * first one will see frame format 0 and have fsize == 0, so we won't
 	 * screw stkadj.
 	 */
-	if (fsize)
+	if (fsize) {
 		regs->stkadj = fsize;
-
-	/* Prepare to skip over the extra stuff in the exception frame.  */
-	if (regs->stkadj) {
-		struct pt_regs *tregs =
-			(struct pt_regs *)((ulong)regs + regs->stkadj);
+		tregs = rte_regs(regs);
 		pr_debug("Performing stackadjust=%04lx\n", regs->stkadj);
-		/* This must be copied with decreasing addresses to
-                   handle overlaps.  */
 		tregs->vector = 0;
 		tregs->format = 0;
-		tregs->pc = regs->pc;
 		tregs->sr = regs->sr;
 	}
+
+	/*
+	 * Set up registers for signal handler.  All the state we are about
+	 * to destroy is successfully copied to sigframe.
+	 */
+	wrusp ((unsigned long) frame);
+	tregs->pc = (unsigned long) ksig->ka.sa.sa_handler;
+	adjustformat(regs);
+
 	return 0;
 }
 
@@ -963,7 +965,8 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 			   struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame;
-	int fsize = frame_extra_sizes(regs->format);
+	struct pt_regs *tregs = rte_regs(regs);
+	int fsize = frame_extra_sizes(tregs->format);
 	int err = 0, sig = ksig->sig;
 
 	if (fsize < 0) {
@@ -1012,34 +1015,27 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 
 	push_cache ((unsigned long) &frame->retcode);
 
-	/*
-	 * Set up registers for signal handler.  All the state we are about
-	 * to destroy is successfully copied to sigframe.
-	 */
-	wrusp ((unsigned long) frame);
-	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
-	adjustformat(regs);
-
 	/*
 	 * This is subtle; if we build more than one sigframe, all but the
 	 * first one will see frame format 0 and have fsize == 0, so we won't
 	 * screw stkadj.
 	 */
-	if (fsize)
+	if (fsize) {
 		regs->stkadj = fsize;
-
-	/* Prepare to skip over the extra stuff in the exception frame.  */
-	if (regs->stkadj) {
-		struct pt_regs *tregs =
-			(struct pt_regs *)((ulong)regs + regs->stkadj);
+		tregs = rte_regs(regs);
 		pr_debug("Performing stackadjust=%04lx\n", regs->stkadj);
-		/* This must be copied with decreasing addresses to
-                   handle overlaps.  */
 		tregs->vector = 0;
 		tregs->format = 0;
-		tregs->pc = regs->pc;
 		tregs->sr = regs->sr;
 	}
+
+	/*
+	 * Set up registers for signal handler.  All the state we are about
+	 * to destroy is successfully copied to sigframe.
+	 */
+	wrusp ((unsigned long) frame);
+	tregs->pc = (unsigned long) ksig->ka.sa.sa_handler;
+	adjustformat(regs);
 	return 0;
 }
 
-- 
2.33.0




  parent reply	other threads:[~2021-10-14 15:00 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14 14:54 [PATCH 4.19 00/12] 4.19.212-rc1 review Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 01/12] net: phy: bcm7xxx: Fixed indirect MMD operations Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 02/12] HID: apple: Fix logical maximum and usage maximum of Magic Keyboard JIS Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 03/12] netfilter: ip6_tables: zero-initialize fragment offset Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 04/12] mac80211: Drop frames from invalid MAC address in ad-hoc mode Greg Kroah-Hartman
2021-10-14 14:54 ` Greg Kroah-Hartman [this message]
2021-10-14 14:54 ` [PATCH 4.19 06/12] net: prevent user from passing illegal stab size Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 07/12] mac80211: check return value of rhashtable_init Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 08/12] net: sun: SUNVNET_COMMON should depend on INET Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 09/12] scsi: ses: Fix unsigned comparison with less than zero Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 10/12] scsi: virtio_scsi: Fix spelling mistake "Unsupport" -> "Unsupported" Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 11/12] perf/x86: Reset destroy callback on event init failure Greg Kroah-Hartman
2021-10-14 14:54 ` [PATCH 4.19 12/12] sched: Always inline is_percpu_thread() Greg Kroah-Hartman
2021-10-14 18:32 ` [PATCH 4.19 00/12] 4.19.212-rc1 review Jon Hunter
2021-10-14 21:07 ` Pavel Machek
2021-10-14 22:39 ` Shuah Khan
2021-10-15  7:20 ` Samuel Zou
2021-10-15 14:33 ` Sudip Mukherjee
2021-10-15 17:34 ` Daniel Díaz
2021-10-15 22:06 ` Guenter Roeck

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211014145206.732488174@linuxfoundation.org \
    --to=gregkh@linuxfoundation.org \
    --cc=fthain@linux-m68k.org \
    --cc=geert@linux-m68k.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=sashal@kernel.org \
    --cc=schmitzmic@gmail.com \
    --cc=stable@vger.kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.