2006-10-04 17:57:55

by Martin Schwidefsky

Subject: [S390] user-copy optimization fallout.

From: Martin Schwidefsky <[email protected]>

[S390] user-copy optimization fallout.

Fix new restore_sigregs function. It copies the user space copy of the
old psw without correcting the psw.mask and the psw.addr high order bit.
While we are at it, simplify save_sigregs a bit.

Signed-off-by: Martin Schwidefsky <[email protected]>
---

arch/s390/kernel/signal.c | 17 +++++++----------
1 files changed, 7 insertions(+), 10 deletions(-)

diff -urpN linux-2.6/arch/s390/kernel/signal.c linux-2.6-patched/arch/s390/kernel/signal.c
--- linux-2.6/arch/s390/kernel/signal.c 2006-10-04 19:53:26.000000000 +0200
+++ linux-2.6-patched/arch/s390/kernel/signal.c 2006-10-04 19:53:45.000000000 +0200
@@ -113,17 +113,15 @@ sys_sigaltstack(const stack_t __user *us
/* Returns non-zero on fault. */
static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
- unsigned long old_mask = regs->psw.mask;
_sigregs user_sregs;

save_access_regs(current->thread.acrs);

/* Copy a 'clean' PSW mask to the user to avoid leaking
information about whether PER is currently on. */
- regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
- memcpy(&user_sregs.regs.psw, &regs->psw, sizeof(sregs->regs.psw) +
- sizeof(sregs->regs.gprs));
- regs->psw.mask = old_mask;
+ user_sregs.regs.psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
+ user_sregs.regs.psw.addr = regs->psw.addr;
+ memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
memcpy(&user_sregs.regs.acrs, current->thread.acrs,
sizeof(sregs->regs.acrs));
/*
@@ -139,7 +137,6 @@ static int save_sigregs(struct pt_regs *
/* Returns positive number on error */
static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
- unsigned long old_mask = regs->psw.mask;
int err;
_sigregs user_sregs;

@@ -147,12 +144,12 @@ static int restore_sigregs(struct pt_reg
current_thread_info()->restart_block.fn = do_no_restart_syscall;

err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
- regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);
- regs->psw.addr |= PSW_ADDR_AMODE;
if (err)
return err;
- memcpy(&regs->psw, &user_sregs.regs.psw, sizeof(sregs->regs.psw) +
- sizeof(sregs->regs.gprs));
+ regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
+ user_sregs.regs.psw.mask);
+ regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
+ memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
sizeof(sregs->regs.acrs));
restore_access_regs(current->thread.acrs);