lkml.org 
[lkml]   [2017]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] x86/kernel/process_32: Convert a smp_processor_id() call
Hi,

this is on 32-bit with tip/master.

I *think* the solution is as straight-forward but pls double-check me on
that.

Thanks.

---
From: Borislav Petkov <bp@suse.de>
Date: Sun, 28 May 2017 11:03:42 +0200
Subject: [PATCH] x86/kernel/process_32: Convert a smp_processor_id() call

... to raw_smp_processor_id() to not trip the

BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1

check. The reasoning behind it is that __warn() already uses the raw_
variants but the show_regs() path on 32-bit doesn't.

Otherwise, you get splat in a splat:

Write protecting the kernel read-only data: 2980k
NX-protecting the kernel data: 4744k
x86/mm: Found insecure W+X mapping at address c00a0000/0xc00a0000
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at .../arch/x86/mm/dump_pagetables.c:236 note_page+0x6ca/0x8e0
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2+ #1
Hardware name: LENOVO 30515QG/30515QG, BIOS 8RET30WW (1.12 ) 09/15/2011
task: f4120000 task.stack: f411a000
EIP: note_page+0x6ca/0x8e0
BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
caller is debug_smp_processor_id
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2+ #1
Hardware name: LENOVO 30515QG/30515QG, BIOS 8RET30WW (1.12 ) 09/15/2011
Call Trace:
dump_stack
check_preemption_disabled
debug_smp_processor_id
__show_regs
? note_page
? printk
? show_regs_print_info
? note_page
show_regs
? vprintk_func
? note_page
__warn
? note_page
? note_page
report_bug
do_trap
? do_error_trap
? __this_cpu_preempt_check
? trace_hardirqs_on_caller
do_error_trap
? note_page
? wake_up_klogd
? console_unlock
? common_exception
? do_overflow
? __this_cpu_preempt_check
? trace_hardirqs_off_caller
? do_overflow
do_invalid_op
common_exception
EIP: note_page+0x6ca/0x8e0
EFLAGS: 00210286 CPU: 0
EAX: 00000041 EBX: f411bf40 ECX: 00000000 EDX: c10bd629
ESI: 80000000 EDI: 00000000 EBP: f411bf0c ESP: f411bed4
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
? wake_up_klogd
? do_overflow
? change_page_attr_set_clr
ptdump_walk_pgd_level_core
ptdump_walk_pgd_level_checkwx
mark_rodata_ro
? rest_init
kernel_init
? schedule_tail_wrapper
ret_from_fork
EFLAGS: 00210286 CPU: 0
EAX: 00000041 EBX: f411bf40 ECX: 00000000 EDX: c10bd629
ESI: 80000000 EDI: 00000000 EBP: f411bf0c ESP: f411bed4
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
CR0: 80050033 CR2: ffbff000 CR3: 01bbe000 CR4: 000006f0
Call Trace:
? change_page_attr_set_clr
ptdump_walk_pgd_level_core
ptdump_walk_pgd_level_checkwx
mark_rodata_ro
? rest_init
kernel_init
? schedule_tail_wrapper
ret_from_fork
---[ end trace e1a49e2b8e42d056 ]---
x86/mm: Checked W+X mappings: FAILED, 96 W+X pages found.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/process_32.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index ff40e74c9181..ffeae818aa7a 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -78,7 +78,7 @@ void __show_regs(struct pt_regs *regs, int all)

printk(KERN_DEFAULT "EIP: %pS\n", (void *)regs->ip);
printk(KERN_DEFAULT "EFLAGS: %08lx CPU: %d\n", regs->flags,
- smp_processor_id());
+ raw_smp_processor_id());

printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
--
2.11.0

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

\
 
 \ /
  Last update: 2017-05-28 11:23    [W:0.087 / U:1.656 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site