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[POWERPC] Make alignment exception always check exception table

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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 <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Benjamin Herrenschmidt 2006-11-01 15:11:39 +11:00 committed by Paul Mackerras
parent 0d69a052d4
commit 4393c4f678
2 changed files with 20 additions and 16 deletions
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18
arch/powerpc/kernel/traps.c
View File

@ -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)

18
arch/ppc/kernel/traps.c
View File

@ -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)