evie/android_kernel_oneplus_msm8998
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arm: kernel: Ignore KASan errors from unwind_frame

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When a process A unwind the stack frame of process B,
the stack of B can be modified and updated in other CPU
concurrently. So KASan could examine stack address with
out of date shadow mask value. To avoid this incorrect
KASan report, disable KASan during unwinding a frame of
a different task.

Following is the Kasan error log for the reference.

==================================================================
BUG: KASan: out of bounds access in unwind_frame+0x9c/0xf8 at addr ffffffc0462b76f0
Read of size 8 by task Signal Catcher/1282
page:ffffffbac7bdb260 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x0()
page dumped because: kasan: bad access detected
Call trace:
[<ffffffc00008c010>] dump_backtrace+0x0/0x250
[<ffffffc00008c270>] show_stack+0x10/0x1c
[<ffffffc001b6e628>] dump_stack+0x74/0xfc
[<ffffffc0002dd7c4>] kasan_report_error+0x2b0/0x408
[<ffffffc0002dd9f8>] kasan_report+0x34/0x40
[<ffffffc0002dda78>] __asan_report_load8_noabort+0x14/0x20
[<ffffffc00008b984>] unwind_frame+0x98/0xf8
[<ffffffc00008ba14>] walk_stackframe+0x30/0x48
[<ffffffc00008bba4>] save_stack_trace_tsk+0x178/0x254
[<ffffffc0003a5bc4>] proc_pid_stack+0xf0/0x198
[<ffffffc0003a11b0>] proc_single_show+0xe8/0x130
[<ffffffc000330e0c>] seq_read+0x524/0xaf0
[<ffffffc0002e9c74>] vfs_read+0x120/0x270
[<ffffffc0002eb208>] SyS_read+0xec/0x198
Memory state around the buggy address:
 ffffffc0462b7580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffc0462b7600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffc0462b7680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                                ^
 ffffffc0462b7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffc0462b7780: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00
==================================================================

Change-Id: I0e35e6721417fa7a5bffb41be67443cd906e256a
Signed-off-by: Se Wang (Patrick) Oh <sewango@codeaurora.org>
This commit is contained in:
Se Wang (Patrick) Oh 2015-06-25 19:38:38 -07:00 • committed by Rohit Vaswani
parent a1efe43c52
commit dbd6607ac7
2 changed files with 10 additions and 0 deletions
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5
arch/arm/kernel/stacktrace.c
View file

@ -1,4 +1,5 @@
#include <linux/export.h>
#include <linux/kasan.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
@ -35,11 +36,15 @@ int notrace unwind_frame(struct stackframe *frame)
if (fp < low + 12 || fp > high - 4)
return -EINVAL;
kasan_disable_current();
/* restore the registers from the stack frame */
frame->fp = *(unsigned long *)(fp - 12);
frame->sp = *(unsigned long *)(fp - 8);
frame->pc = *(unsigned long *)(fp - 4);
kasan_enable_current();
return 0;
}
#endif

5
arch/arm64/kernel/stacktrace.c
View file

@ -15,6 +15,7 @@
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/sched.h>
@ -46,10 +47,14 @@ int notrace unwind_frame(struct stackframe *frame)
if (fp < low || fp > high - 0x18 || fp & 0xf)
return -EINVAL;
kasan_disable_current();
frame->sp = fp + 0x10;
frame->fp = *(unsigned long *)(fp);
frame->pc = *(unsigned long *)(fp + 8);
kasan_enable_current();
return 0;
}