From 4393c4f6788cee65095dd838cfeca6edefbfeb52 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 1 Nov 2006 15:11:39 +1100 Subject: [PATCH] [POWERPC] Make alignment exception always check exception table The alignment exception used to only check the exception table for -EFAULT, not for other errors. That opens an oops window if we can coerce the kernel into getting an alignment exception for other reasons in what would normally be a user-protected accessor, which can be done via some of the futex ops. This fixes it by always checking the exception tables. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/traps.c | 18 ++++++++++-------- arch/ppc/kernel/traps.c | 18 ++++++++++-------- 2 files changed, 20 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 5ed4c2ceb5ca..c66b4771ef44 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -843,7 +843,7 @@ void __kprobes program_check_exception(struct pt_regs *regs) void alignment_exception(struct pt_regs *regs) { - int fixed = 0; + int sig, code, fixed = 0; /* we don't implement logging of alignment exceptions */ if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS)) @@ -857,14 +857,16 @@ void alignment_exception(struct pt_regs *regs) /* Operand address was bad */ if (fixed == -EFAULT) { - if (user_mode(regs)) - _exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar); - else - /* Search exception table */ - bad_page_fault(regs, regs->dar, SIGSEGV); - return; + sig = SIGSEGV; + code = SEGV_ACCERR; + } else { + sig = SIGBUS; + code = BUS_ADRALN; } - _exception(SIGBUS, regs, BUS_ADRALN, regs->dar); + if (user_mode(regs)) + _exception(sig, regs, code, regs->dar); + else + bad_page_fault(regs, regs->dar, sig); } void StackOverflow(struct pt_regs *regs) diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c index aafc8e8893d1..9661a91183b3 100644 --- a/arch/ppc/kernel/traps.c +++ b/arch/ppc/kernel/traps.c @@ -708,7 +708,7 @@ void single_step_exception(struct pt_regs *regs) void alignment_exception(struct pt_regs *regs) { - int fixed; + int sig, code, fixed = 0; fixed = fix_alignment(regs); if (fixed == 1) { @@ -717,14 +717,16 @@ void alignment_exception(struct pt_regs *regs) return; } if (fixed == -EFAULT) { - /* fixed == -EFAULT means the operand address was bad */ - if (user_mode(regs)) - _exception(SIGSEGV, regs, SEGV_ACCERR, regs->dar); - else - bad_page_fault(regs, regs->dar, SIGSEGV); - return; + sig = SIGSEGV; + code = SEGV_ACCERR; + } else { + sig = SIGBUS; + code = BUS_ADRALN; } - _exception(SIGBUS, regs, BUS_ADRALN, regs->dar); + if (user_mode(regs)) + _exception(sig, regs, code, regs->dar); + else + bad_page_fault(regs, regs->dar, sig); } void StackOverflow(struct pt_regs *regs) -- 2.20.1