* stack out-of-bounds write in mce-inject.c
@ 2018-04-27 15:24 Dmitry Vyukov
2018-04-27 15:41 ` Borislav Petkov
0 siblings, 1 reply; 6+ messages in thread
From: Dmitry Vyukov @ 2018-04-27 15:24 UTC (permalink / raw)
To: tony.luck, Borislav Petkov, Thomas Gleixner, Ingo Molnar,
H. Peter Anvin, the arch/x86 maintainers, linux-edac, LKML
Hi,
Opening /sys/kernel/debug/mce-inject/flags overwrites stack:
==================================================================
BUG: KASAN: stack-out-of-bounds in vsnprintf+0x1b23/0x1b40 lib/vsprintf.c:2365
Write of size 1 at addr ffff8800627b7abb by task egrep/4309
CPU: 3 PID: 4309 Comm: egrep Not tainted 4.17.0-rc2+ #179
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:366 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:424
__asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:447
vsnprintf+0x1b23/0x1b40 lib/vsprintf.c:2365
sprintf+0xa7/0xd0 lib/vsprintf.c:2494
flags_read+0xa3/0xf0 arch/x86/kernel/cpu/mcheck/mce-inject.c:345
full_proxy_read+0x125/0x190 fs/debugfs/file.c:195
__vfs_read+0x10f/0xa50 fs/read_write.c:416
vfs_read+0x17f/0x3d0 fs/read_write.c:452
ksys_read+0xf9/0x250 fs/read_write.c:578
__do_sys_read fs/read_write.c:588 [inline]
__se_sys_read fs/read_write.c:586 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:586
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb17c6c3310
RSP: 002b:00007ffca98af8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000001d72000 RCX: 00007fb17c6c3310
RDX: 0000000000008000 RSI: 0000000001d72000 RDI: 0000000000000005
RBP: 0000000000001000 R08: 0000000001d72000 R09: 00007fb17c979e90
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000008000 R14: 0000000000000000 R15: 0000000000000003
The buggy address belongs to the page:
page:ffffea000189edc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea0001890101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8800627b7980: f3 f3 f3 f3 00 00 00 00 00 00 00 f1 f1 f1 f1 00
ffff8800627b7a00: 00 00 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00
>ffff8800627b7a80: 00 00 00 f1 f1 f1 f1 03 f2 f2 f2 f3 f3 f3 f3 00
^
ffff8800627b7b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8800627b7b80: 00 00 00 00 00 f1 f1 f1 f1 00 00 f2 f2 f2 f2 f2
==================================================================
On upstream commit 0644f186fc9d77bb5bd198369e59fb28927a3692.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: stack out-of-bounds write in mce-inject.c
2018-04-27 15:24 stack out-of-bounds write in mce-inject.c Dmitry Vyukov
@ 2018-04-27 15:41 ` Borislav Petkov
2018-04-27 16:06 ` Dmitry Vyukov
0 siblings, 1 reply; 6+ messages in thread
From: Borislav Petkov @ 2018-04-27 15:41 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: tony.luck, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
the arch/x86 maintainers, linux-edac, LKML
On Fri, Apr 27, 2018 at 05:24:24PM +0200, Dmitry Vyukov wrote:
> Hi,
>
> Opening /sys/kernel/debug/mce-inject/flags overwrites stack:
>
> ==================================================================
> BUG: KASAN: stack-out-of-bounds in vsnprintf+0x1b23/0x1b40 lib/vsprintf.c:2365
> Write of size 1 at addr ffff8800627b7abb by task egrep/4309
How do you trigger this exactly?
You grep it for something apparently...
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: stack out-of-bounds write in mce-inject.c
2018-04-27 15:41 ` Borislav Petkov
@ 2018-04-27 16:06 ` Dmitry Vyukov
2018-04-27 16:37 ` [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read() Luck, Tony
0 siblings, 1 reply; 6+ messages in thread
From: Dmitry Vyukov @ 2018-04-27 16:06 UTC (permalink / raw)
To: Borislav Petkov
Cc: tony.luck, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
the arch/x86 maintainers, linux-edac, LKML
On Fri, Apr 27, 2018 at 5:41 PM, Borislav Petkov <bp@alien8.de> wrote:
> On Fri, Apr 27, 2018 at 05:24:24PM +0200, Dmitry Vyukov wrote:
>> Hi,
>>
>> Opening /sys/kernel/debug/mce-inject/flags overwrites stack:
>>
>> ==================================================================
>> BUG: KASAN: stack-out-of-bounds in vsnprintf+0x1b23/0x1b40 lib/vsprintf.c:2365
>> Write of size 1 at addr ffff8800627b7abb by task egrep/4309
>
> How do you trigger this exactly?
>
> You grep it for something apparently...
find /sys -exec grep "64" {} \; -print
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read()
2018-04-27 16:06 ` Dmitry Vyukov
@ 2018-04-27 16:37 ` Luck, Tony
2018-04-27 16:59 ` Borislav Petkov
2018-05-06 10:52 ` [tip:ras/core] x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read() tip-bot for Luck, Tony
0 siblings, 2 replies; 6+ messages in thread
From: Luck, Tony @ 2018-04-27 16:37 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: Borislav Petkov, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
the arch/x86 maintainers, linux-edac, LKML
Each of the strings that we want to put into the buf[MAX_FLAG_OPT_SIZE]
in flags_read() is two characters. But the sprintf() adds a trailing newline
and will add a terminating NUL byte. So MAX_FLAG_OPT_SIZE needs to be 4.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c
index 475cb4f5f14f..c805a06e14c3 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -48,7 +48,7 @@ static struct dentry *dfs_inj;
static u8 n_banks;
-#define MAX_FLAG_OPT_SIZE 3
+#define MAX_FLAG_OPT_SIZE 4
#define NBCFG 0x44
enum injection_type {
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read()
2018-04-27 16:37 ` [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read() Luck, Tony
@ 2018-04-27 16:59 ` Borislav Petkov
2018-05-06 10:52 ` [tip:ras/core] x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read() tip-bot for Luck, Tony
1 sibling, 0 replies; 6+ messages in thread
From: Borislav Petkov @ 2018-04-27 16:59 UTC (permalink / raw)
To: Luck, Tony
Cc: Dmitry Vyukov, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
the arch/x86 maintainers, linux-edac, LKML
On Fri, Apr 27, 2018 at 09:37:08AM -0700, Luck, Tony wrote:
> Each of the strings that we want to put into the buf[MAX_FLAG_OPT_SIZE]
> in flags_read() is two characters. But the sprintf() adds a trailing newline
> and will add a terminating NUL byte. So MAX_FLAG_OPT_SIZE needs to be 4.
... and I dumped the n here:
n = sprintf(buf, "%s\n", flags_options[inj_type])
and it was 3 but sprintf() calls vsnprintf() and *that* does return:
" * The return value is the number of characters which would
* be generated for the given input, excluding the trailing
* '\0', as per ISO C99."
So I'll extend the commit message with that and apply it.
Thanks.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
^ permalink raw reply [flat|nested] 6+ messages in thread* [tip:ras/core] x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read()
2018-04-27 16:37 ` [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read() Luck, Tony
2018-04-27 16:59 ` Borislav Petkov
@ 2018-05-06 10:52 ` tip-bot for Luck, Tony
1 sibling, 0 replies; 6+ messages in thread
From: tip-bot for Luck, Tony @ 2018-05-06 10:52 UTC (permalink / raw)
To: linux-tip-commits
Cc: dvyukov, tony.luck, tglx, linux-kernel, mingo, hpa, bp, linux-edac
Commit-ID: 985c78d3ff8e9c74450fa2bb08eb55e680d999ca
Gitweb: https://git.kernel.org/tip/985c78d3ff8e9c74450fa2bb08eb55e680d999ca
Author: Luck, Tony <tony.luck@intel.com>
AuthorDate: Fri, 27 Apr 2018 09:37:08 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 6 May 2018 12:46:39 +0200
x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read()
Each of the strings that we want to put into the buf[MAX_FLAG_OPT_SIZE]
in flags_read() is two characters long. But the sprintf() adds
a trailing newline and will add a terminating NUL byte. So
MAX_FLAG_OPT_SIZE needs to be 4.
sprintf() calls vsnprintf() and *that* does return:
" * The return value is the number of characters which would
* be generated for the given input, excluding the trailing
* '\0', as per ISO C99."
Note the "excluding".
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20180427163707.ktaiysvbk3yhk4wm@agluck-desk
---
arch/x86/kernel/cpu/mcheck/mce-inject.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c
index 475cb4f5f14f..c805a06e14c3 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-inject.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c
@@ -48,7 +48,7 @@ static struct dentry *dfs_inj;
static u8 n_banks;
-#define MAX_FLAG_OPT_SIZE 3
+#define MAX_FLAG_OPT_SIZE 4
#define NBCFG 0x44
enum injection_type {
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-05-06 10:52 UTC | newest]
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2018-04-27 15:24 stack out-of-bounds write in mce-inject.c Dmitry Vyukov
2018-04-27 15:41 ` Borislav Petkov
2018-04-27 16:06 ` Dmitry Vyukov
2018-04-27 16:37 ` [PATCH] x86, mce: Fix stack out-of-bounds write in mce-inject.c:flags_read() Luck, Tony
2018-04-27 16:59 ` Borislav Petkov
2018-05-06 10:52 ` [tip:ras/core] x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read() tip-bot for Luck, Tony
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