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s390/compat: correct uc_sigmask of the compat signal frame

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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: Stefan Liebler <stli@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2015-09-08 15:25:39 +02:00
parent 9380cf5a88
commit 8d4bd0ed04
1 changed files with 23 additions and 4 deletions
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27
arch/s390/kernel/compat_signal.c
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@ -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;