It's a userland pointer; worse, an untrustable one since ptrace
has just provided a chance to modify it.
X-Roothole-Covering-Cabal: TINRCC
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
arch/m32r/kernel/signal.c | 38 +++++++++++++++++---------------------
1 files changed, 17 insertions(+), 21 deletions(-)
diff --git a/arch/m32r/kernel/signal.c b/arch/m32r/kernel/signal.c
index a56fcbd..7bbe386 100644
--- a/arch/m32r/kernel/signal.c
+++ b/arch/m32r/kernel/signal.c
@@ -251,6 +251,19 @@ give_sigsegv:
return -EFAULT;
}
+static int prev_insn(struct pt_regs *regs)
+{
+ u16 inst;
+ if (get_user(&inst, (u16 __user *)(regs->bpc - 2)))
+ return -EFAULT;
+ if ((inst & 0xfff0) == 0x10f0) /* trap ? */
+ regs->bpc -= 2;
+ else
+ regs->bpc -= 4;
+ regs->syscall_nr = -1;
+ return 0;
+}
+
/*
* OK, we're invoking a handler
*/
@@ -259,8 +272,6 @@ static int
handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *oldset, struct pt_regs *regs)
{
- unsigned short inst;
-
/* Are we from a system call? */
if (regs->syscall_nr >= 0) {
/* If so, check system call restarting.. */
@@ -278,12 +289,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
/* fallthrough */
case -ERESTARTNOINTR:
regs->r0 = regs->orig_r0;
- inst = *(unsigned short *)(regs->bpc - 2);
- if ((inst & 0xfff0) == 0x10f0) /* trap ? */
- regs->bpc -= 2;
- else
- regs->bpc -= 4;
- regs->syscall_nr = -1;
+ if (prev_insn(regs) < 0)
+ return -EFAULT;
}
}
@@ -310,7 +317,6 @@ static void do_signal(struct pt_regs *regs)
siginfo_t info;
int signr;
struct k_sigaction ka;
- unsigned short inst;
sigset_t *oldset;
/*
@@ -353,21 +359,11 @@ static void do_signal(struct pt_regs *regs)
regs->r0 == -ERESTARTSYS ||
regs->r0 == -ERESTARTNOINTR) {
regs->r0 = regs->orig_r0;
- inst = *(unsigned short *)(regs->bpc - 2);
- if ((inst & 0xfff0) == 0x10f0) /* trap ? */
- regs->bpc -= 2;
- else
- regs->bpc -= 4;
- regs->syscall_nr = -1;
+ prev_insn(regs);
} else if (regs->r0 == -ERESTART_RESTARTBLOCK){
regs->r0 = regs->orig_r0;
regs->r7 = __NR_restart_syscall;
- inst = *(unsigned short *)(regs->bpc - 2);
- if ((inst & 0xfff0) == 0x10f0) /* trap ? */
- regs->bpc -= 2;
- else
- regs->bpc -= 4;
- regs->syscall_nr = -1;
+ prev_insn(regs);
}
}
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
--
1.5.6.5
--
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