Impact: fix redundant and incorrect check
Oleg Nesterov noticed wrt commit:
14fc9fb: x86: signal: check signal stack overflow properly
>> No need to check SA_ONSTACK if we're already using alternate signal stack.
>
> Yes, but this also mean that we don't need sas_ss_flags() under
> "if (!onsigstack)",
Checking on_sig_stack() in sas_ss_flags() at get_sigframe() is redundant
and not correct on 64 bit. To check sas_ss_size is enough.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: roland@redhat.com
LKML-Reference: <49CBB54C.5080201@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Check alternate signal stack overflow with proper stack pointer.
The stack pointer of the next signal frame is different if that
task has i387 state.
On x86_64, redzone would be included.
No need to check SA_ONSTACK if we're already using alternate signal stack.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Roland McGrath <roland@redhat.com>
LKML-Reference: <49C2874D.3080002@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix bad frame in rt_sigreturn on 64-bit
After commit 97286a2b64 some applications
fail to return from signal handler:
[ 145.150133] firefox[3250] bad frame in rt_sigreturn frame:00007f902b44eb28 ip:352e80b307 sp:7f902b44ef70 orax:ffffffffffffffff in libpthread-2.9.so[352e800000+17000]
[ 665.519017] firefox[5420] bad frame in rt_sigreturn frame:00007faa8deaeb28 ip:352e80b307 sp:7faa8deaef70 orax:ffffffffffffffff in libpthread-2.9.so[352e800000+17000]
The root cause is forgetting to keep 64 byte aligned value of
fpstate for next stack pointer calculation.
Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
LKML-Reference: <49AC85C1.7060600@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Add missing __user annotation to the parameter of get_sigframe().
Also change cast type to void __user * of *fpstate.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
With the recent changes in the 32-bit code to make system calls which
use struct pt_regs take a pointer, sys_rt_sigreturn() have become
identical between 32 and 64 bits, and both are empty wrappers around
do_rt_sigreturn(). Remove both wrappers and rename both to
sys_rt_sigreturn().
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it. This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to take the pointer as an argument instead of relying on
the assumption that the pt_regs structure overlaps the function
arguments.
Drop the use of regparm(1) due to concern about gcc bugs, and to move
in the direction of the eventual removal of regparm(0) for asmlinkage.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it. This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to regparm(1) to receive the pt_regs pointer as the
first argument.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
On x86_32, %gs is handled lazily. It's not saved and restored on
kernel entry/exit but only when necessary which usually is during task
switch but there are few other places. Currently, it's done by
calling savesegment() and loadsegment() explicitly. Define
get_user_gs(), set_user_gs() and task_user_gs() and use them instead.
While at it, clean up register access macros in signal.c.
This cleans up code a bit and will help future changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: use new framework
Use {get|put}_user_try, catch, and _ex in arch/x86/kernel/signal.c.
Note: this patch contains "WARNING: line over 80 characters", because when
introducing new block I insert an indent to avoid mistakes by edit.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This reverts commit 4217458daf.
Justin Madru bisected this commit, it was causing weird Firefox
crashes.
The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.
So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.
Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505
Reported-and-bisected-by: Justin Madru <jdm64@gawab.com>
Tested-by: Justin Madru <jdm64@gawab.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, move header file
Move arch/x86/kernel/sigframe.h to arch/x86/include/asm/sigframe.h.
It will be used in arch/x86/ia32/ia32_signal.c.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Move declarations of ia32_setup_rt_frame() and ia32_setup_frame() into
arch/x86/kernel/signal.c.
This is for future use of sigframe.h.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Call signal_fault() in error route of sys_sigreturn().
Change log level to KERN_EMERG if current is init.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup on 32-bit
Peter pointed this parameter can be changed.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
