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Commit 8d4bd0ed authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/compat: correct uc_sigmask of the compat signal frame 



The uc_sigmask in the ucontext structure is an array of words to keep
the 64 signal bits (or 1024 if you ask glibc but the kernel sigset_t
only has 64 bits).

For 64 bit the sigset_t contains a single 8 byte word, but for 31 bit
there are two 4 byte words. The compat signal handler code uses a
simple copy of the 64 bit sigset_t to the 31 bit compat_sigset_t.
As s390 is a big-endian architecture this is incorrect, the two words
in the 31 bit sigset_t array need to be swapped.

Cc: <stable@vger.kernel.org>
Reported-by: default avatarStefan Liebler <stli@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 9380cf5a

arch/s390/kernel/compat_signal.c

+23 −4
Original line number Diff line number Diff line
@@ -48,6 +48,19 @@ typedef struct 
	struct ucontext32 uc;

} rt_sigframe32;



static inline void sigset_to_sigset32(unsigned long *set64,

				      compat_sigset_word *set32)

{

	set32[0] = (compat_sigset_word) set64[0];

	set32[1] = (compat_sigset_word)(set64[0] >> 32);

}



static inline void sigset32_to_sigset(compat_sigset_word *set32,

				      unsigned long *set64)

{

	set64[0] = (unsigned long) set32[0] | ((unsigned long) set32[1] << 32);

}



int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)

{

	int err;
@@ -281,10 +294,12 @@ COMPAT_SYSCALL_DEFINE0(sigreturn) 
{

	struct pt_regs *regs = task_pt_regs(current);

	sigframe32 __user *frame = (sigframe32 __user *)regs->gprs[15];

	compat_sigset_t cset;

	sigset_t set;



	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE32))

	if (__copy_from_user(&cset.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE32))

		goto badframe;

	sigset32_to_sigset(cset.sig, set.sig);

	set_current_blocked(&set);

	save_fpu_regs();

	if (restore_sigregs32(regs, &frame->sregs))
@@ -302,10 +317,12 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn) 
{

	struct pt_regs *regs = task_pt_regs(current);

	rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];

	compat_sigset_t cset;

	sigset_t set;



	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))

	if (__copy_from_user(&cset, &frame->uc.uc_sigmask, sizeof(cset)))

		goto badframe;

	sigset32_to_sigset(cset.sig, set.sig);

	set_current_blocked(&set);

	if (compat_restore_altstack(&frame->uc.uc_stack))

		goto badframe;
@@ -377,7 +394,7 @@ static int setup_frame32(struct ksignal *ksig, sigset_t *set, 
		return -EFAULT;



	/* Create struct sigcontext32 on the signal stack */

	memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE32);

	sigset_to_sigset32(set->sig, sc.oldmask);

	sc.sregs = (__u32)(unsigned long __force) &frame->sregs;

	if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))

		return -EFAULT;
@@ -438,6 +455,7 @@ static int setup_frame32(struct ksignal *ksig, sigset_t *set, 
static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set,

			    struct pt_regs *regs)

{

	compat_sigset_t cset;

	rt_sigframe32 __user *frame;

	unsigned long restorer;

	size_t frame_size;
@@ -485,11 +503,12 @@ static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set, 
	store_sigregs();



	/* Create ucontext on the signal stack. */

	sigset_to_sigset32(set->sig, cset.sig);

	if (__put_user(uc_flags, &frame->uc.uc_flags) ||

	    __put_user(0, &frame->uc.uc_link) ||

	    __compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||

	    save_sigregs32(regs, &frame->uc.uc_mcontext) ||

	    __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||

	    __copy_to_user(&frame->uc.uc_sigmask, &cset, sizeof(cset)) ||

	    save_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))

		return -EFAULT;